New year, new quiz, old bugs, and help with rate laws

Happy New Year, everyone! I hope 2023 has started well for you and your students. I wanted to let you know about a brand new quiz that I just finished as well as some important bug fixes, and I also wanted to ask for help with the next quiz I’d like to write.

Brand new quiz!

*NEW* Scientific Measurements Quiz – thanks, Fionna!

  • make accurate scientific measurements using diagrams of rulers, graduated cylinders and thermometers
  • fill-in-the-blank or multiple choice questions

Here are some examples of the diagrams generated by this new quiz:

large graduated cylinder diagram from Scientific Measurements Quiz small graduated cylinder diagram from Scientific Measurements Quiz.png thermometer diagram from Scientific Measurements Quiz
ruler diagram from Scientific Measurements Quiz

I received a suggestion to write this quiz about two years ago, but I kept putting it off because I didn’t know how to generate dynamic drawings beyond the isotope notation in the Nuclear Reactions Quiz. However, I started working on this quiz a few months ago when I was learning to generate dynamic drawings of particles for the Types of Matter Quiz because I needed measurement diagrams for my own Chemistry students, who haven’t had much hands-on lab experience so far thanks to the pandemic. I’m not sure if you’re seeing this with your students, but even simple tasks like estimating a digit between the lines on a ruler or taking a reading at the bottom of the meniscus have been challenging to mine.

So, I made some ruler and graduated cylinder diagrams that I used in class to try to help them, but I needed winter break to have time to sit down and figure out how to generate those diagrams dynamically and accurately. Once I finished the quiz, I also added alcohol thermometers for fun, if any of you are still using those with your students, but I stopped short at adding triple beam balances (for now!). I know that many of you won’t need this quiz until next fall, but I hope it’s helpful now for those of you who teach on a block schedule or in college and are just starting with your Chemistry students.

Disabled “Enter” key on all quizzes

I was talking with one of my Computer Science students (who’s taking Chemistry with one of my colleagues) about and he told me how frustrated he was when he accidentally pressed the “enter” key and submitted his answers before he was done with the quiz, and he had to start all over. I felt that he made a really good point, so I looked into adding a popup window or a modal dialog box to verify that a student was ready to submit their answers, but I found that the least disruptive way to prevent accidental submission would be to disable the “enter” key altogether.

This means that in order to have their responses graded, students must now click the pink “Grade it!” button. I’m hoping this eliminates any frustration your students may have experienced with this issue! Please let me know if you notice any problems with this change, or if your students encounter any other difficulties or issues while using

Lots of bug fixes

It’s difficult to find the time and mental energy to sit down and focus on fixing bugs on while school is in session, especially when some of the code was written a long time ago back when the quizzes were on my school blog. That’s why I tried to focus on knocking out as many as possible during this winter break so that the site runs as smoothly as possible for the rest of the school year. Here’s a list of everything that has been fixed recently


  • when creating a new assignment, the “Require student login” setting was saving as “checked” even when unchecked
  • student quiz result times were not adjusting correctly for the school’s time zone on Results and Grades pages
  • clicking on the “Results” link on the Students page would not show that student correctly on the Results page

Bond Polarity & Electronegativity Quiz

  • entering “0” for electronegativity difference (Δχ) now correctly registers as “0” instead of “no answer” (thanks to my students!)
  • added “fuzziness” option of +/- 0.1 for electronegativity difference (Δχ) values (also suggested by my students)

Hess’s Law Quiz

  • incorrect heat values were being pulled from the database when grading (thanks Terrie, Thomas and Elena!)

Mass Ratios, Percent Composition & Empirical Formulas Quiz

  • empirical formulas with polyatomic ions are now counted as correct (thanks, Scott!)

Molar Conversions Quiz

  • answers less than 0.01 were showing up as 0 but not being accepted (thanks Scott, Theresa, Danny and Carol! I’m really sorry that this bug caused so much frustration to so many people)

Molecular Geometry & VSEPR Quiz

  • changed wording to “unbonded electron pairs *around the central atom*” (thanks, Susan!)

Naming Compounds & Calculating Molar Masses Quiz

  • also accepts “aluminium” for compound names (suggested by one of my students who used the IUPAC spelling from her periodic table)
  • H2O2 and O3 are no longer included in the quiz

Periodic Trends Quiz

  • added multiple choice questions
  • added option to select representative elements (s- and p-blocks) and/or transition metals (d-block)
  • quiz wasn’t available in the Dashboard (thanks, Rohunke!)

Other improvements

If I didn’t fix a bug or issue that you’ve reported, I’ll do my best to address it as soon as I can!

Help with new rate laws quiz?

I’ve received several requests over the past couple years to write a quiz on kinetics and rate laws, but I have to admit that I’ve never really taught it, so I don’t have a deep understanding of it, and I don’t have a lot of resources beyond what I can find online and in the textbooks that I have laying around. In order to write a dynamically generated quiz, I need to be able to visualize the kinds of questions and problems it would generate based on repeating patterns, so the more types of problems I can see and categorize, the better.

If you have any good materials that you’d be willing to share with me, such as worksheets or assessments (especially with keys!), I would very much appreciate it, and I promise not to share them with anyone else! It doesn’t have to be anything fancy; even a quick picture of a worksheet would help. Thanks in advance!

Help me share with the world!

If you like using, there are three quick and easy things that you can do to help me promote the site!

  • Follow @ChemQuizDotNet on Twitter and Facebook and share my updates with your fellow Chemistry teachers!
  • Tell another Chemistry teacher about and encourage them to try out the Dashboard!
  • Add your school to the list of supporters on the About page by going to the Dashboard, click on “Your Info” in the top menu bar, check the box next to “Display School on“, and click the “Update Your Info” button.

Here’s hoping that 2023 is a great year for all of us! Please contact me any time if you have any questions or suggestions for improvement, or if you run into any problems while using Take care, stay safe, and as always, thanks so much for your support!


New newsletter service, three new quizzes, Dashboard improvements & other fixes

Hi there! I hope you’ve had a good school year so far, and I hope those of you who are in the United States and Canada had a Happy Thanksgiving. I wanted to squeeze in one more round of updates before the end of the calendar year in the hopes that they might be useful for you and your students.

Speaking of the end of the calendar year, I have two fun chemistry activities that I’m excited that I finally get to do again: making borax snowflakes and silvering glass bottles for holiday ornaments! I’ve saved up a lot of empty hot sauce bottles over the years so that I could use them with my AP Physics 2 classes, which were small, but I think I might have just enough to use for my CP Chemistry classes this year. If you want to try this with your students, small glass vials work well. Just make sure they know to never open the vial again after it’s silvered!

Now that I’m teaching Chemistry again, I’ve been able to test out features and prototype new quizzes with my students as we move through the curriculum. Some of my students have been pretty, uh, frank with their criticisms (they’re almost all sophomores), so it’s been fun getting their feedback! 🤣 It’s also really interesting watching them figure chemistry concepts out by taking the practice quizzes on the site, asking me questions as they go. I had no idea getting the confetti that shows up when they earn a perfect score would be so motivating! I’ve had kids try quizzes over and over again until they get every question correct just so they can see that animation. I don’t know how many of you are working on earning a higher degree and need to do educational research, but there’s definitely something worth studying about the motivational power of confetti! 🎉

Now using Mailchimp for the newsletter

You may have noticed that the newsletter is a little different from the previous versions. Unfortunately, the last time I tried to send it out directly from my website in early October, but there are so many teachers on the mailing list now that my mail program crashed. As a result, I think many of you never received the October newsletter. As much as I prefer to use tools I’ve written myself, I’m going to try Mailchimp for now and see how it works. Just like before, the newsletter is “opt in” only, so if you don’t want to receive it in the future, please reply with “Unsubscribe” or click the link at the bottom of the email. The last thing I want to do is bug my fellow science teachers! (By the way, if you ever want to look at past newsletters, they’re archived in the News section of the website.)

Three new quizzes

*NEW* Average Atomic Masses Quiz

  • calculate average atomic masses for fictional elements using different precisions
  • fill-in-the-blank or multiple choice questions

*NEW* Periodic Trends Quiz (thanks, Lorraine & Nora!)

  • identify elements based on periodic trends across groups and periods
  • compare atomic mass, atomic radius, effective nuclear charge, electron affinity, electronegativity, first ionization energy, and ionic radius
  • multiple choice questions coming very soon!

*NEW* Types of Matter Quiz (thanks, Kendra & Brankica!)

  • identify types and states of matter from particle diagrams
  • multiple choice questions about diagrams justifying answers

New Dashboard features & bug fixes

Now that I’m using the Dashboard with my own classes on a regular basis, I’ve noticed some shortcomings and annoyances that I’ve tried to fix. I’ve also added a few little features that I think could make everyone’s lives a little easier.

  • Multiple teachers from the same school can now share the same class (thanks, Danny!)
  • Assignments that have been started but not completed are now hidden by default on the Results page but can be shown through the filter menu
  • Added an “archive” action link to the Assignments page
    teachers can now preview inactive quizzes
  • Bug fix: switching the class filter on the Grades incorrectly returned teachers to the first page of scores (thanks again, Danny!)
  • Bug fix: assignments were showing up on the Dashboard for the wrong students when “All Classes” was selected by another teacher at the same school

Quiz bug fixes & minor updates

Calorimetry Quiz

  • thermal equilibrium word problems for c2 and m2 weren’t showing T1 (thanks, Sylvie!)

Electron Configuration Quiz

  • Fixed question language to use the phrase “electrons in a subshell” or “electrons in the 3p orbitals” (plural) instead of “3p orbital” (thanks, Rob!)

Hess’s Law Quiz

  • fixed question language to read “standard heats of formation” (thanks, Matthew!)

Lewis Dot Structures Quiz

  • Fixed an error with “How many dots could be drawn in a Lewis dot structure for an element that can form 0 chemical bonds? ” question not handling zero correctly (thanks a third time, Danny!)
  • Lewis dot structure symbols were displaying incorrectly in presentation mode

Molecular Geometry & VSEPR Quiz

  • When the student was given a simple white + pink ball-and-stick model (X-A), it was actually assessing the question based on a model with 2 white balls and 1 pink ball (X-A-X) (thanks, David!)

Other bug fixes

  • added updated login info for Google users to the Join page
  • PHPmailer stopped working, so assignment email scripts were switched to wp_mail instead

The primary way I find out about bugs is from the teachers and students who use the site, so please keep the bug reports coming! You can submit a bug by emailing me at, or filling out the Contact form on the site. I do my best to fix bugs as quickly as possible, but since I’m also a full-time teacher, there are some days where there just isn’t enough mental energy left for me to figure it out after school. Because of that, I do most of my development work on the weekend and over breaks, and I focus on site licenses and user account issues during the week. I appreciate your patience as I try to grow and improve the site!

Help me share with the world!

If you like using, there are three quick and easy things that you can do to help me promote the site!

  • Follow @ChemQuizDotNet on Twitter and Facebook and share my updates with your fellow Chemistry teachers!
  • Tell another Chemistry teacher about and encourage them to try out the Dashboard!
  • Add your school to the list of supporters on the About page by going to the Dashboard, click on “Your Info” in the top menu bar, check the box next to “Display School on“, and click the “Update Your Info” button.

I hope the last few weeks before the end of 2022 go smoothly for you and your students. Please feel free to drop me a line if you have any questions, suggestions for improvement, or problems with the site. Take care, stay safe, and have a happy New Year!


Hosting upgrade, login issues, and bug fixes

Hello, everyone! I hope your new school year has started off well with as few bumps and disruptions as possible. Despite enduring two lockdowns at school last month, I’m having a lot of fun teaching Chemistry again because I get to do neat stuff like making “gold” pennies:

video of a zinc-coated penny being turned to brass

This is from the Alchemy Lab that I’ve been doing for decades and which is a student favorite – here are the directions if you’re interested! There are lots of ways to do the lab, but this year I had my students heat their pennies on hotplates instead of in Bunsen burner flames, and that seemed to work much better. (On a side note: today when I was testing Bunsen burners and bleeding air that had built up in the gas lines in the lab over the summer, one of them suddenly shot flames out from the bottom and burned off some of the hair on my knuckles, so I’m happy to stick with hotplates instead! 🔥)

Since the start of September, over 20 schools have either signed up for new site licenses or renewed from last school year, so I wanted to thank you all for your continued support of! These site licenses allowed me to upgrade to faster web hosting last month to make the site run faster. Speaking of the upgrade…

September 21st hosting upgrade (or, “The best laid plans of mice and men”)

I’ve noticed that the site was getting WAY more traffic in August 2022 than it did in August 2021, and there were more issues with “site not responding” errors due to my web hosting tier being overwhelmed, so I used money from site licenses to upgrade my web hosting. Based on the documentation on my hosting service’s website, it seemed really easy – contact sales, pay for the upgrade. The process probably took me a total of five minutes, at most!

Unfortunately, the sales team must not have communicated with the tech support team, because while the guts of got moved to a new server and IP address, none of the domain name service (DNS) entries got updated, so for about 24 hours, loading up would take you to the old server, not the new one that I’d paid for. When I finally realized what was going on the following day, it took about two hours of tech support chat and phone calls to get everything sorted out.

Without getting into the gory details, DNS updates propagate across the world from the server they’re originally changed on, one server connection at a time, so it can take up to 48 hours for the changes to take effect everywhere in the world. This means that for about a day and a half, some users were accessing the new, faster hosting, while others were accessing the old, slower hosting. The quizzes all acted the same, but some quiz results were saved to the old server and then “disappeared” as soon as the DNS update went through.

The good news is that I still had access to the old server, so I waited until DNS had fully propagated by Saturday afternoon and then copied those missing results over to the new server. I only copied over important quiz result and user data, so you can see switchover clearly on this graph of site visits over the last 20 days since I didn’t bother copying the database table with those stats:
graph of visits over the past 20 days

If it still appears that any of your students’ quiz results are missing from the Dashboard, please let me know and I’ll double check for you! I know how much students hate it when a teacher loses their work, so I don’t want that to happen to any of your students on

Student login issues

I’ve been hearing from a number of teachers with site licenses to the Dashboard that their students are sometimes having problems accessing during the day. There are two primary reasons this has been happening: an overall increase in the number of visitors to the site, and the security software interpreting failed student logins as hacking. I’ve upgraded the web hosting to address the first, as I mentioned earlier, but the second issue is a little more complicated.

Basically, if a student repeatedly attempts to log in with an incorrect password (or no password at all) and fails 10 times in a row, the site’s security software will block that student’s IP address for 5 minutes. The idea is to prevent “brute force” hacking, which unfortunately is very common on sites like that are based on the WordPress content management system. (You would not believe how frequently the website is attacked from all over the world – it’s a constant issue.) This student behavior may be unintentional or completely intentional, but the effect is the same, and it can prevent your other students from accessing the site if they have the same IP address, which is common for school districts.

Unfortunately, I can’t disable the security software, because would get hacked within days, if not hours. However, to prevent this sort of lockout from happening to you and your students, there are two steps you can take. First, you can send me your school or district IP address at school by googling “What’s my IP address” and send me the number. I’ll whitelist your IP address so that any failed login attempts are ignored by the site security software. Make sure you do this at school, not at home! The second thing you can do is monitor your students when they’re logging in to to make sure they’re not just clicking the login button repeatedly. The good news is that their login sessions last for 30 days since the last time they’ve accessed the site, so between that and the “Login with Google” button, I’m hoping this won’t continue to be a serious issue going forward.

New features & bug fixes

No new quizzes with this update, but thanks to your feedback, I’ve made some serious bug fixes that were impeding assignment creation on the Dashboard. Here’s a summary of the bug fixes:

  • disabled autocomplete in all form inputs for all quizzes so that entering answers is a cleaner experience for students (suggested by my son!)
  • students couldn’t load all of the options to practice a quiz if an assignment already existed for it (thanks, Danny!)
  • threshold, notes, instructions and custom name were being wiped out in the database when a new assignment was created in the Dashboard (thanks, Ryan!)
  • “lock after close” could be set without a value for “date closed” when creating & editing assignments (thanks, Krisha!)
  • can’t edit quiz-specific options for an assignment in the Dashboard if it has a due date (thanks, Darlene!)
  • archived classes were showing up in filter menu on the Results page in the Dashboard (I found this one)
  • + other under-the-hood Dashboard improvements
  • answers on the Concentrations of Solutions Quiz that were correctly rounded to the hundredths place were marked as incorrect (thanks, Karen!)
  • the Lewis Dot Structures Quiz wasn’t identifying all correct student responses, so now the quiz just counts the number of checkboxes to match the correct number of valence electrons (thanks, Nick & David!)
  • some two-step conversion problems in the SI Conversions Quiz were converting to the same unit 🤦🏻‍♂️ (thanks again, Darlene!)

Help me share with the world!

If you like using, there are three quick and easy things that you can do to help me promote the site!

  • Follow @ChemQuizDotNet on Twitter and Facebook and share my updates with your fellow Chemistry teachers!
  • Tell another Chemistry teacher about and encourage them to try out the Dashboard!
  • Add your school to the list of supporters on the About page by going to the Dashboard, click on “Your Info” in the top menu bar, check the box next to “Display School on“, and click the “Update Your Info” button.

There was a funny moment this weekend when our oldest kid, who’s a first-year student at Ohio University, was visiting us up in Kent this past weekend. Our son is a freshman taking Advanced Chemistry with a colleague of mine at the high school where I teach, and he was complaining about how he missed some questions on a recent sig figs quiz in class. Unprompted by me, our oldest said, “Use ChemQuiz to practice sig figs, it’s easy!” I wish I’d had my phone in hand so I could have recorded the exchange for future advertising purposes, but all I have is the memory. 😂

Thanks again to everyone for your continued support of and for your patience with the bumps in the road that have occurred recently. Please feel free to get in touch with me if you have any questions, suggestions for improvement, or problems with the site. Take care and stay safe!


PS: If you didn’t see the September newsletter because of email delivery issues, it’s available here!


New Lab Equipment Quiz and more

Good afternoon, and Happy Labor Day to all of my fellow Americans! For those of you who have started school already, like I have, I hope everything has gone smoothly so far, and for those of you about to start, I hope it goes well. As I mentioned in a previous newsletter, due to resignations and staff reductions at my school, my Climate Science and AP Physics 2 courses were axed and I was switched back to teaching CP Chemistry for the first time since the 2013-2014 school year. I’ve been surprised to find that I’ve been able to get back into the groove pretty quickly after only two weeks with my Chem students. I’m pretty sure that writing and tweaking the chemistry practice quizzes for have kept that knowledge in the forefront of my brain! Teaching Chemistry again also allows me to do fun demos like this:

a test tube containing hydrochloric acid, universal indicator and sodium carbonate produces a pretty rainbow patternIf you’re interested in doing this demo, simply add 0.1M HCl to a test tube until it’s about 2/3 full, add enough universal indicator to make it really red and stir, then hold the test tube at an angle and add saturated sodium carbonate (also known as “washing soda”) dropwise. The sodium carbonate is more dense than the hydrochloric acid, so it slides right down the side of the tube and raises the pH so that it turns dark blue. This was a real showstopper when I did it in class last week, and it leads to all kinds of great questions and discussions, so I highly recommend it for all levels!

5 million visits!

a screenshot of the statistics page from

This past Thursday, September 1st, broke 5 million visits since the site went live in June 2020! On the same day, the site set a new record for total vists (40,752) and unique visitors (3,749). The record from the 2021-2022 school year was 30,520 visits on February 8th, 2022, so I’m expecting another year of exciting growth for the site. Since the site is currently averaging just under 4 million visits per 365 days, I’m wondering if it’ll hit 10 million visits by the end of this school year. Maybe! Either way, I’m absolutely flabbergasted by the numbers and how much the site is being used.

Site licenses

Thank you SO MUCH to everyone who has purchased a site license for their school for the 2022-2023 school year! I truly appreciate your support and trust as we’re all gearing up for a third year of pandemic teaching. For those of you haven’t purchased a site license yet, make sure you check your demo expiration date by logging in to the Dashboard and clicking on “School Info” in the top menu. I extended a number of demo accounts through the end of September, so if you’re thinking about purchasing a site license, you have until then to play around with all the Dashboard features.

If you’re interested in purchasing a site license for the 2022-2023 school year, the cost is US$50 per year per school or college instructor, and I can accept payment through school purchase order, personal check, credit card through Square, or CashApp, PayPal, Venmo and Zelle at If you’re outside the United States, please use one of the electronic payment methods above. If you teach in a high poverty public high school or school district (at least 50% of your students on free/reduced lunch or designated “economically disadvantaged”), then send me a link to the supporting documentation and you’ll get a site license for free forever. I’m still strongly committed to making a part of leveling the playing field for STEM students around the United States!

New quiz!

a diagram from shows an erlenmeyer flask pouring water into a beaker

*NEW* Laboratory Equipment Quiz!

  • 75 items and OSHA safety symbols commonly found in the chemistry lab with names, diagrams and descriptions
  • excellent equipment diagrams from Chemix! (used with permission)
  • fill-in-the-blank option for naming equipment and safety symbols; multiple choice options for diagrams and descriptions

This quiz was a lot of fun to write, and now that I’m teaching Chemistry again, I’m looking forward to using it with my own students to see how much it helps them learn all of the different lab equipment that we have. We spent an entire school day this past Friday with every Chemistry student emptying out the lab drawers, sorting the equipment, cleaning the glassware and drawers, and restocking the drawers with the correct kinds and amounts of equipment in our two chem classrooms. We found some stuff that had been in there for close to a decade, if not longer. 😳 Thanks to Susan for the quiz suggestion!

New features & bug fixes

Between getting ready to teach Chemistry again and trying to organize the diagrams and descriptions for the Lab Equipment Quiz, I focused on adding new features that have been requested by teachers and also on fixing bugs that either caused serious problems or gave users a weird experience. Some of these requests go back over a year, so I apologize if yours took a while to complete!

New Dashboard features & bug fixes

  • looking at the detailed assignment result will now show all attempts by that student for that assignment to show growth (if any)
  • teachers can now generate a printable or presentation version of an assignment with their selected settings from the Assignments page (thanks Barry!)
  • teachers can now add students to a class through the “Bulk actions” menu on the Users page
  • added a file attachment field to the Contact form for screenshots to make it easier to report bugs
  • bug fix: CSV user import from a Google Sheet wasn’t working because Google changed its access parameters for Sheets
  • bug fix: CSV import should handle apostrophes in student names correctly now
  • bug fix: lost password link was hijacked by the WooCommerce plug-in (thanks Rhonda!)
  • bug fix: the “requireLogin” setting for assignments had the wrong name in checkbox 🤦🏻‍♂️ (thanks David!)
  • bug fix: copying an assignment in the Dashboard produced an error due to a bad MySQL query (thanks Barry!)
  • bug fix: adding student accounts by CSV import wasn’t adding students to classes because of a string misspelling 🤦🏻‍♂️🤦🏻‍♂️

New quiz features & bug fixes

General updates
  • added CONFETTI for when a student earns an achievement or a perfect score on quiz with 10 or more items (I know this one is silly, but it makes me laugh every time I see it so I hope your students like it too – you can preview the confetti if you’re curious!)
  • made “under-the-hood” improvements for various quiz functions
  • bug fix: quiz options logging was slowing down the site significantly, so I turned it off until I can improve its performance (logging is only to see how often certain options are being used, it doesn’t track users)
  • bug fix: turning off session_start() in the logging function allowed students to go back after submitting quiz, so I re-enabled PHP sessions (thanks Anamar!)
Balancing, Identifying & Predicting Chemical Equations Quiz
  • added multiple choice questions (I hope to do this someday for all the quizzes, but it can be really challenging to come up with good distractors that are dynamically generated)
  • added physical states to chemical equations (thanks Don!)
Bond Polarity & Electronegativity Quiz
  • bug fix: delta notation was giving wrong answers (thanks Matthew!)
Calorimetry Quiz
  • added “drop hot metal into cold water, what’s the final temperature?” problems (thanks Ken & Sylvie!)
  • added ~20 specific heats of metals to the database
Density Calculations Quiz
  • added g/L and kg/L density units (thanks Sylvie!)
Gas Laws Quiz
  • made the wanted value more obvious with listed givens
  • bug fix: gas names weren’t showing up with listed givens
Mass Ratios, Percent Composition & Empirical Formulas Quiz
  • added “percent composition from masses” and “empirical formula from masses” questions (thanks Holly!)
  • added an option for word problems
Naming Compounds & Calculating Molar Masses Quiz
  • added an option for compounds with common polyatomic ions (thanks Barbara!)
  • made the random selection of givens more evenly distributed (thanks for the suggestion Grant! Over time I’m going to go back and implement the code I developed for this to all of the quizzes)
Organic Nomenclature Quiz
  • added aromatic compounds
  • bug fix: compounds with rings and halides were not being selected properly
Redox Reactions & Net Ionic Equations Quiz
  • changed question wording so that it says “substance” instead of “compound” (thanks Matt!)
Scientific Notation Quiz
  • added challenging “determine prefix” problems
  • added counting the number of sig figs in the answer (thanks Carla!)
  • bug fix: quiz wasn’t handling × (times symbol) correctly in answers (thanks Joseph!)
Significant Figures Quiz
  • bug fix: gave the wrong answer for addition/subtract problems when both givens had decimal points (thanks Kelli!)
Stoichiometry & Limiting Reagents Quiz
  • added physical states to chemical equations (thanks Don!)
Thermochemical Equations Quiz
  • added physical states to chemical equations (thanks Don!)

Thanks again to everyone who made suggestions or reported bugs so that I could make these improvements! If you have an idea for a new feature or quiz, or you come across something that’s not working correctly, please let me know by emailing me at, or you can fill out the easy-to-use Contact form.

Help me share with the world!

If you like using, there are three quick and easy things that you can do to help me promote the site!

  • Follow @ChemQuizDotNet on Twitter and Facebook and share my updates with your fellow Chemistry teachers!
  • Tell another Chemistry teacher about and encourage them to try out the Dashboard!
  • Add your school to the list of supporters on the About page by going to the Dashboard, click on “Your Info” in the top menu bar, check the box next to “Display School on“, and click the “Update Your Info” button.

In mid-August, we moved our oldest kid into the dorm for their first year at Ohio University, where they’ll be majoring in Wildlife Conservation Biology while also playing flute in the symphonic band (because flutes aren’t allowed in the OU marching band – go figure!), so our house feels a little emptier than usual. If you’ve been through this milestone, then you already know the weird mixture of emotions it can bring. Personally, like a typical dad, I’ve been keeping myself busy working on so I don’t have to confront my own feelings. 😂

I know I’ve said it many times, but thanks again for all of your support – whether you just signed up this week or you’ve been collaborating with me for the past decade – because it makes this little venture all the more enjoyable. Please feel free to reach out any time if you have any questions, concerns, suggestions or feedback. Take care, stay safe, and good luck this school year!



Looking forward to the 2022-2023 school year

Hi, everybody! I hope you’re all doing well and have been able to get some rest and relax a bit after the challenges we faced this past school year. On a personal note, I was able to take the family up to the Upper Peninsula of Michigan for a few days in July – what a beautiful place! We stayed in the tiny town of Grand Marais on the southern shore of Lake Superior for a few days and took in some of the local sights. If you’re ever able to make it up there and you like seeing trees more than having cell service, I highly recommend it!

I’ve put a lot of time and effort into this summer to write new quizzes and improve the Dashboard so that the site is more useful for you and your students this upcoming school year. I’m really excited about all the new stuff I have to share with you, so let’s get right to it!

New quizzes!

*NEW* Bond Polarity & Electronegativity Quiz

  • determine polarity, arrow notation and delta notation of chemical bonds
  • calculate electronegativity difference (Δχ or ΔEN)

*NEW* Molecular Geometry & VSEPR Quiz

  • identify molecular shape, electron geometry and AXE notation of chemical compounds
  • determine polarity, ideal bond angle(s), electron hybridization and number of domains, unbonded pairs and total valence electrons

*NEW* Organic Nomenclature Quiz

  • name organic compounds from over 9,000 chemical diagrams
  • identify organic compound classes such as alcohols, aldehydes, amines, esters, ethers, ketones and more

*NEW* Redox Reactions & Net Ionic Equations Quiz

  • write net ionic equations when given chemical reactions
  • determine oxidation numbers in over 1,000 compounds and identify oxidizing and reducing agents in reactions
  • balance over 100 redox reactions in acidic and basic solutions

I had a lot of fun writing these quizzes and learned a lot while working on them, from AXE notation to using PubChemPy to interface with PubChem to drawing molecules with SMILES. I feel like they fill in some of the gaps in topics that I had before and I hope they provide you and your students with lots of useful practice questions!

New features

I received some really helpful feedback from the end-of-the-year survey that I sent out last spring about how the Dashboard could be better, so I’ve made the following improvements:

New Dashboard features for teachers:

  • NEW “Gradebook” feature provides easier to read results in a grid
  • NEW Teacher Discussion Forum for communicating with other Chemistry teachers around the world – ask for help, point out bugs, etc! (FYI you must be logged into your teacher account to access the forum)
  • moved the sample curriculum to Dashboard as “Exemplars” (more on this in a bit)
  • teachers can now create assignments that don’t require students to log in – great for quick check for understanding or “bell ringer”! – just share the link with them
  • teachers can now require an access code for assignments – helpful if you have multiple sections of the same course throughout the day and want to restrict access
  • added a checkbox at the top of the Results table to select all results so teachers can archive them in a bulk action
  • teachers can now see which students have started an assignment but haven’t finished

Because of some personnel changes, the school where I teach switched me back to Chemistry again – for the first time in eight years! – so that made me really sit down and think about how to make the Dashboard work better for classroom teachers who have limited time to figure their way around a complicated user interface, so I really hope the improvements are noticeable and helpful.

More new features for teachers:

  • users can log in through Google using the “Log in with Google” button on the Login page – if your district uses Google, this should help your students who have login issues!
  • custom assignment names now show at the top of quizzes
  • added “Name:” line & custom title options to the top of printable quizzes

New Dashboard features for students:

  • added a menu bar for better organization
  • students can now change their own password
  • added a big pink “Go to Dashboard” button on home page that shows up if they’re logged in
  • cute new artwork by Rain Carman for Significant Figures Quiz and Gas Laws Quiz!

Our school district uses Google and my son is taking Chemistry this year with one of my colleagues, so I’ve been testing the Google login with him and I’m hoping it’ll make the site a lot easier to use for everyone in the Google ecosystem.

Bug fixes

Unfortunately, there will always be bugs with any software, but I’ve been able to fix a number of them thanks to the help of many teachers and students:

  • automated assignment and result emails are working properly again!
  • filter menu for assignments Results didn’t show all assignments if any archived results existed for that teacher (thanks Jason!)
  • couldn’t remove “Assignment due date” on existing assignments (thanks Matthew!)
  • Scientific Notation Quiz wouldn’t load proper settings in printable mode
  • Solubility Quiz wasn’t calculating answers for ions correctly (thanks Susan!)
  • Enthalpy Calculations Quiz wasn’t calculating answers for mass (g) correctly (thanks again, Susan!)
  • percent yield problems in the Stoichiometry & Limiting Reagents Quiz with a given product and wanted reactant quantity were not calculating correctly (thanks Don!)
  • many other small fixes and under-the-hood improvements and optimizations

I still have a few more bugs I’m trying to track down and squish before my school year starts in the next couple weeks! If you come across something that’s not working properly on, please let me know by emailing me or filling out the Contact form on the site. Sometimes I can find and fix a bug quickly, while other times it takes me a while to reproduce the error and figure out what it’s happening, but rest assured that I document them all and will try my best to resolve them.

NEW Independent Student Accounts!

I’ve always tried to make as accessible as possible by making the quizzes free for everyone to use and giving out free site licenses to schools with high proportions of economically disadvantaged students. However, I’ve been contacted in the past by students whose teachers aren’t using the Dashboard but want to work on their own and keep track of their own progress, especially when preparing for an exam.

To that end, I’ve created a new Independent Student Account option that features over 150 scaffolded assignments across the 30 quizzes on the site! As students complete the assignments, they’ll earn “Achievement Badges” based on the number they’ve passed as well as the quizzes or topics they’ve finished. Students can also hide topics that don’t apply to their studies; for example, I imagine a lot of high school students will hide the Organic Nomenclature assignments. Here’s what independent students will see when they log in:

screenshot of independent student account Dashboard
screenshot of independent student account Dashboard

Here’s a picture of the “Neon Badge”, which an independent student will earn after completing 10 assignments:

Neon Achievement Badge
Neon Achievement Badge

(atomic #10, get it? 😂)

I’m hoping that Independent Student Accounts will help make even more useful to Chemistry students around the world, regardless of whether their teachers use the Dashboard, so I’m keeping the price low at just US $6 for a full year of access. As I write more quizzes and add more features to existing quizzes, I’ll keep creating assignments that will be available at no additional charge. Please reach out if you have any questions about Independent Student Accounts!

By the way, these assignments are available for teachers with Dashboard site licenses to use too! Just log in to the Dashboard and click on the new “Exemplars” link in the top menu bar:

screenshot of Dashboard menu bar with Exemplars activated
Exemplars in the Dashboard

From there, you can select an exemplar (example assignment) and create a copy of it to assign to your own students and modify however you’d like. These are many of the same assignments I plan on using in my CP Chemistry classes this upcoming school year, so I hope they’re also helpful for you!

Dashboard site licenses for the 2022-2023 school year

A number of you have already purchased a site license to the Dashboard for the 2022-2023 school year – thanks again for your support! Site licenses help me pay for the web hosting and other software that I use to write and publish the quizzes. They also help me justify the time I’ve spent developing the site instead of applying for more supplementals at school (like I’m sure many of you have done!). Site licenses are good through July 1, 2023, unless your school district operates on a different academic calendar, in which case I can modify that access window to meet your needs.

If you’re interested in purchasing a site license for the 2022-2023 school year, the cost remains US$50 per year, and I can accept payment through a variety of means, including school purchase orders, personal check, a credit card through Square, or you can send payment to at CashApp, PayPal, Venmo or Zelle. If you’re outside the United States, please try to use one of the electronic payment methods above, as my credit union has made depositing foreign checks difficult.

I’ve sent out a lot of sales quotes and invoices recently, but if you didn’t receive one or need another copy, please let me know! If you’re planning on paying with a school purchase order, I’m happy to fill out whatever forms your district requires and I’ll activate your site license as soon as I get the PO.

Remember, if you teach in a high poverty public high school or school district (at least 50% of your students on free/reduced lunch or designated “economically disadvantaged”), then just send me a link to the supporting documentation and you’ll get a site license for free forever. There are currently 73 public schools in the United States that are taking advantage of the free site license to help their students learn Chemistry, and it makes me really happy that I can offer that service to them at no cost.

Help get the word out about!

If you like, there are three quick and easy things that you can do to help me promote the site!

  • Follow @ChemQuizDotNet on Twitter and Facebook and share my updates with your fellow Chemistry teachers!
  • Tell another Chemistry teacher about and encourage them to try out the Dashboard!
  • Add your school to the growing list of supporters on the About page by going to the Dashboard, click on “Your Info” in the top menu bar, check the box next to “Display School on“, and click the “Update Your Info” button.

Collaborating with science teachers all around the world over the past two years has been the most rewarding aspect of creating (although I did get a really nice email from a student who told me that, thanks to the site, she passed Chemistry and was planning on majoring in it, so that might win!) so I wanted to thank you for all of your kind words, helpful suggestions and constructive criticism. With all of the modern classroom stresses of bed bugs, covid, school shootings and now monkeypox, it’s nice to have something positive like this that I can focus my efforts on. I’m looking forward to another great school year of serving up Chemistry practice quizzes!



Wrapping up the 2021-2022 school year

Hello again! I hope this email finds you well, and I hope that the 2021-2022 school year is wrapping up or has already wrapped up for you. I know that this was a challenging year for a lot of teachers, including me and my colleagues where I teach, so it’ll be nice to disconnect and get some physical and mental rest this summer.

Website stats

This school year has seen a lot of success for! The site has seen about 3.6 million hits over the last calendar year, and it frequently gets over 2,000 unique visitors per day. The top three most popular quizzes on the site, based on total visits so far, are:

The least popular quiz is the Solubility Quiz, with only 4,686 visits over the past two years. Poor thing – I guess no one likes solubility!

Additionally, there have been 21,613 quiz results recorded on the Dashboard since July 1st of last year, and overall, over 417,000 quizzes have been taken on the site since I started counting on January 15 of this year. It seems likely that the site is providing a million randomly generated chemistry quizzes each calendar year, which is just incredible to think about. It wouldn’t have been possible without your support!

Site license renewals

Site licenses for the Dashboard are how I pay for the web hosting and the software I use to write the quizzes, and it keeps the website ad-free. You may have noticed that the site’s hosting was upgraded over winter break and loads much faster now, and that was paid for with the money from site licenses. I’ve already sent out invoices to all of my current paying customers for next school year, but if you didn’t receive one, please let me know.

If you have a demo account and would like to purchase a site license for the 2022-2033 school year for just $US50, you can purchase it through a school purchase order or personal check, or via CashApp, PayPal, Venmo or Zelle at, or I can send you an invoice through Square for a credit card payment. If you have any questions at all about site licenses or how to purchase one, please reach out to me at any time!

As always, I am strongly committed to helping students at economically disadvantaged public schools in the United States learn chemistry and science. There are currently 70 schools or school districts that are receiving a free site license to the Dashboard for this reason. If you teach in a high poverty public high school or school district (at least 50% of your students on free/reduced lunch or designated “economically disadvantaged”), please send me a link to the supporting documentation and you’ll get a free site license for the Dashboard. For what it’s worth, I verify demographics through the U.S. News High School Rankings website, so you can just send me the link to your school on there to speed up the process. (BTW I hate the term “economically disadvantaged” because I feel it obfuscates the real reasons behind larger societal problems, but that’s a rant for another day.)

Summer maintenance

The Dashboard has now accumulated over 6,000 users, some of whom last used the site over a year ago, so I’m going to be performing the following maintenance items over the summer, starting on or shortly after July 1st:

  • All quiz results before June 30th will be archived (but not deleted)
  • All assignments before June 30th will be archived (but not deleted)
  • All student accounts created during the 2021-2022 school year (7/1/21 – 6/30/22) will be archived (but not deleted)
  • All student accounts created during the 2020-2021 school year will be deleted

If you don’t want me to archive your stuff, or if you operate on a different school calendar, please let me know before July 1st!

End of school year survey

Last year, I asked every teacher that uses or has signed up for the Dashboard to complete a short survey about how they used the site and what they wanted to see in the future. The feedback I received was really helpful, so if you wouldn’t mind, it would be great if you took a moment to fill out this year’s survey here:

New quizzes coming

I received a LOT of requests for new quizzes and features this school year, and thanks to your suggestions, I was able to add five new quizzes, bringing the total to 26 quizzes about chemistry and other fundamental science topics! Three of the most common requests for new quizzes have been for VSEPR, redox, and reaction rates, so those are the topics I’m planning to tackle as soon as my Environmental Club is done with the State Envirothon Competition in early June. I’ve documented every request that has been sent in, so I’ll do my best to write quizzes for each of the topics that I think will be the most useful for teachers and students.

I also added some new features and fixed some bugs based on emails and bug reports that were sent in, so please keep those coming! Unfortunately, I wasn’t able to squish all of the bugs during the school year, but I have everything documented and I’m going to do my best to fix all of them in the upcoming weeks. If you ever come across something on the site that doesn’t work properly, please don’t hesitate to let me know!

New features coming

I have some new features planned for that I think will make the site more useful for you and your students! One suggestion that I think is an excellent idea is for teachers to be able to create quiz assignments that don’t require students to log in to the Dashboard. This is great for quick practice with the settings you specify without worrying about having kids log in first. Another feature that I’m going to add for Dashboard users is exporting quizzes as CSV files so that you can import them into some of the other great education websites out there such as Quizlet, Gimkit and Kahoot. I have some other additions and enhancements planned, so keep your eyes peeled!

Last year, on a whim, I purchased the domain name after one of my CS students asked me for help with physics and told me that I should start writing physics quizzes as well. Unfortunately, I didn’t have time to do anything with it during the school year, but now that summer break is approaching, I was thinking about putting together some physics quizzes in the same style of If you’re interested in being contacted if and when I get up and running, please send me an email at and I’ll keep you in the loop.

Thanks again for all of your support, suggestions and feedback over the past two years! It’s been really exciting to see this little hobby take on a life of its own. I hope you’ve found to be useful for you and your students during this school year, and I hope it continues to be useful in the future! As always, please feel free to let me know if you have any questions, comments, or concerns. If you’re in the United States, I hope you have a restful and peaceful Memorial Day. Take care, stay safe, and enjoy your summer break!


Happy New Year from!

Hello everyone, and Happy New Year! I hope that you and yours have been able to stay safe and healthy during the pandemic. Now that 1st Semester is ending for many of us, I wanted to let you know about the improvements to over the past few months.

Faster web hosting

First, and most importantly, I upgraded the hosting package for the website! The site should run much faster now, especially when lots of people are using it at once, so I’m hoping this improvement is noticeable and makes the site a little more user friendly.‘s popularity has increased a lot, and the site has frequently had over 15,000 hits and 2,000 unique visitors each weekday since mid-September, which is WAY more than last school year. (Interestingly, the peak was on December 14th, 2021, when there were 2,984 unique visitors and 25,937 hits, so I’m guessing that was due to students preparing for 1st Semester Exams.) The site reached two million total hits to date in November 2021, the vast majority of which came since this past August, so it was definitely time for an upgrade! Thanks to everyone who purchased site licenses this school year so that I could pay for the upgrade. (Please note: as a result of the upgrade, email notifications for assignments are currently not working, but I should have them working soon.)

Three new quizzes

Next, there are three new quizzes since my last newsletter in August:

I hope you find them to be useful for your students. Those three quizzes were all requested by multiple teachers, so thank you to everyone who has contacted me with suggestions, because they really help me prioritize what to work on next. I have more new quizzes planned, so hopefully I’ll be able to find the time over the next few months to work on them.

New quiz features

Two notable quiz improvements: you can now generate empirical formula problems in the Mass Ratios & Percent Composition Quiz, so now it’s called the Mass Ratios, Percent Composition & Empirical Formulas Quiz. Also, I modified the Significant Figures Quiz so that it sometimes randomly adds a few extra zeroes past the decimal point, and you can include random units in problems to make them a little more realistic.

New Dashboard features

I added several new features to the Dashboard, including the following:

  • Make copies of existing assignments
  • Export quiz results by class
  • Export the highest quiz score for each student on a particular assignment
  • Other visual and efficiency improvements

I also recorded several instructional videos for the Dashboard, and I added an “md5 hash” to check if students were using the back button to check and fix their answers on quiz assignments (so you may have heard from one of your students if they tried doing that recently!).

Lots of bug fixes

Of course, there wouldn’t be a update without bug fixes – there currently are 46,000 lines of custom code for the quizzes and other scripts that run the site! – so here’s a list of what I was able to squish with your help:

  • existing student accounts were getting corrupted when they tried to join another class; the registration form now checks to make sure an existing student is logged in before allowing them to join a class by using a join code
  • the registration form was grabbing the wrong user ID when creating a new account with a join code
  • several Dashboard specific bugs:
    • archived classes were showing up on assignment form
    • some assignment settings were wiped out immediately after the assignment was created
    • the “Show individual students” link wasn’t working on the Create Assignment form
    • student names were shown as “First Last” in Quiz Results; “Last, First” made more sense
    • assigning quizzes to “All of your classes” didn’t work properly; I changed the way assignments are linked to classes and students in the database
  • Quiz specific bugs:

+ lots of under-the-hood improvements!

If you come across any other bugs, please let me know and I’ll do my best to fix them!

Equity and opportunity

This school year has been much more difficult than many of us anticipated, including me, so I wanted to celebrate the fact that there are currently 45 high-poverty public schools signed up for, which means 54 teachers and their 762 students are able to access the Dashboard LMS at no cost to themselves or their schools. If you purchased a site license, you’ve helped me pay for the web hosting, SSL certificate, domain registration and other business costs that allow me to give free site licenses to schools that have the fewest resources. There’s a lot of student talent out there in all kinds of places, so I’m hoping that will help more students do well in Chemistry and realize their full potential. Thanks for helping make this possible!

Discounts, for a limited time!

In the spirit of making the Dashboard available to more chemistry students, for those of you who haven’t yet purchased a site license for this school year, I’m now offering a discounted rate of just US$30 through July 1st, 2022! With a site license, you’ll be able to create accounts for all of your students and create as many quiz assignments as you’d like, which lets you track your students’ progress as they master different chemistry skills in line with your own curriculum. More info about the Dashboard is available here.

For existing customers, as a show of my sincere gratitude for your support so far, you can renew your license for next school year now through April 1st for only US$40, which is a 20% discount from the normal rate! This will help me secure the upgraded web hosting for next school year so that the site remains fast and accessible for as many people as possible.

One last thing – if you have a site license, make sure you have your school listed on the “About” page by going to the Dashboard, clicking on “Your Info”, and then checking the box next to “Display School on” and clicking the pink “Update your info” button. (Please note that this is completely optional but it does help support the site for free.)


Thanks again for all of your feedback, suggestions and support! When I started in the summer of 2020, I never could have imagined that it would have grown to have so many teachers and students using it every day. Working on the site has been a true source of joy for me during such a difficult time. As always, take care, stay safe, and keep in touch!



New quizzes and features to start the new school year

Hello there! I hope you’ve been able to take the summer to relax and recharge for this upcoming school year.

First, I’d like to thank you for your support over the past school year. went from being an idea I was tossing around with a few of my colleagues during the 2020 lockdown to an educational website that has added over 1,000 users and has had over 900,000 hits! I’ve truly been humbled by the positive feedback and constructive criticism I’ve received during that time. Numerous teachers (you know who you are!) requested new quizzes, suggested new features and pointed out lots of bugs that helped me improve the site and allow me to focus on doing something positive instead of worrying about covid-19 and what school would look like in the fall.

Several of you have already signed up for site licenses, which is awesome! If you had a free account last year but your school isn’t “economically disadvantaged” (I hate that term, btw) with at least 50% of your students on free/reduced lunch, please consider purchasing a site license this school year for only $50. Website hosting isn’t free, so my first goal by selling site licenses is to break even, and then I’m planning to upgrade the hosting so that runs much faster and can support thousands more Chemistry students and their teachers. I can accept payment through Venmo, Zelle, school purchase order or personal check, so please contact me at if you’re interested in purchasing a site license!

On to the exciting news – LOTS of new features! I’ve been working over the summer to try to squash as many bugs and add as many new features as possible. My focus was on trying to make easier to use while also increasing its usefulness to Chemistry teachers and students, so I hope I’ve accomplished those goals. Here’s what’s new:

New Quizzes!

  • NEW Scientific Notation Quiz
    • convert between scientific notation and decimal notation, includes multiple choice questions
  • NEW Chemical Equilibrium Quiz
    • write chemical equilibrium expressions, convert between Kc and Kp, and calculate equilibrium constants and chemical quantities

Improvements to the Dashboard:

  • teachers can now assign a quiz to multiple classes or students
  • teachers can delete multiple student accounts or generate new passwords for multiple students accounts
  • teachers can archive multiple quiz results once they’ve been reviewed
  • quiz results from 2020-2021 school year have automatically been archived
  • added a giant “join link” popup for teachers to show on the screen for easier student enrollment
  • Dashboard automatically generates a QR code for each assignment
  • cleaned up the overall appearance and improved the interface of the Dashboard
  • custom assignment names now show up in CSV result exports

Additions to documentation:

Improvements to all quizzes:

  • new Presentation mode! (I’m really excited about this!) One question per screen with larger font and immediate correct answer (site license required) – try it out on the Significant Figures Quiz!
  • simpler given values for most quizzes to make math problems easier
  • better scientification notation handling so students can enter a number like “6.02 x 10^23” instead of “6.02E23”
  • fixed formatting on quizzes and results so that they look similar
    improved formatting of “printable” quizzes
  • added cute “Generating Quiz” and “Scoring Quiz” animations!
  • add placeholder text to some input boxes to make wanted values a little more obvious
  • updated the example quizzes on the Sample Chemistry Curriculum page to include new features
  • LOTS of other under-the-hood improvements!

Quiz-specific improvements:

I’m also working on several new features and quizzes that I hope to finish soon:

  • new Lewis dot structures quiz
  • new photon wavelength & frequency quiz
  • new reaction rates quiz
  • better integration of Dashboard features so that they’re faster and easier to use
  • prevent students from resubmitting answers for the same quiz instead of retaking the quiz with new problems
  • more quizzes with multiple choice questions
  • better quiz result filtering in the Dashboard
  • and more!

If you have any suggestions for new quizzes or features, please feel free to drop me a line at any time at or by filling out the Contact form. Also, please spread the word about the site:

Thanks again for all of your support this past school year, and I look forward to doing what I can to make this upcoming school year a little easier for you and your students. Take care and stay safe!


The new year brings three new quizzes and lots of new features

Happy New Year, everyone! I hope you’re all doing well, staying safe, and managing your sanity during this challenging school year. After having some time to work on over Winter Break, I wanted to send you an update to let you know about three new quizzes and a bunch of new features that I hope will make your lives a little easier.

First, the three new quizzes in alphabetical order:

  • Molar Conversions Quiz
    • convert between moles and a variety of units
    • chemical formulas or compound names; simple or word problems
  • Isotope Naming & Notation Quiz
    • name isotopes, determine isotope notation and count number of subatomic particles for hundreds of isotopes
  • Thermochemical Equations Quiz
    • over 100 thermochemical equations with heats of reactions
    • stoichiometry and limiting reagents problems
    • balanced and unbalanced equations; chemical formulas or names; grams and moles; percent yield
    • creating this quiz also added 192 new balanced chemical equations that are used by other quizzes for more variety!

I also added a new score correction feature to the Dashboard that allows you to override quiz items that has erroneously marked as incorrect. Just view the quiz result details, check the box(es) next to the items you’d like to mark as correct, and click the “Save Update” button at the bottom of the page. You can also leave feedback (comments) on quiz results that can be viewed by your students just like in other learning management systems. Another new Dashboard feature is the ability to archive old quiz results so they don’t show up in the list any more unless you want them to be displayed. This has no impact on whether or not a student can see their quiz results, because students can’t currently archive their results. Finally, by request, teachers now have the ability to filter their quiz results by class.

In addition to these new features and quizzes, I made two quick bug fixes, one giving teachers the ability to disable assignment email notifications to students (this option wasn’t displaying correctly before), and some beta decays in the Nuclear Reactions Quiz were generating way too many products, resulting in questions that violated the law of conservation of matter. Oops! There were also some little bug fixes thanks to teacher and student feedback that were mostly focused on simple mistakes, like a student putting an extra space before or after an answer that resulted in an item being marked incorrect when it shouldn’t have been.

The last new feature that I’ve added – reference sheets! For decades I’ve given my students various handouts of equations, ions, etc., as have many of you, but a teacher contacted me asking for a list of the polyatomic ions used the Naming Chemical Compounds Quiz, so I uploaded my reference sheets to Google Drive, updated and tweaked them, and I’ve made them available to you to use with your students. You can make copies in Google Docs or download them as Word documents and modify them however you like, or you can just download them as PDFs and print them for use in your own classroom (if you’re currently teaching in person, like I am). There are reference sheets for ions, common chemical equations, and SI prefixes, but if I’ve left out an important topic, ion, or equation, please let me now!

Finally, check out these cool website visitor stats:

Today (January 5th, 2021) represents the day with the greatest number of hits and unique visitors since began this past summer! You can also clearly see where Thanksgiving and especially Winter Break happened, which was great timing because I used that time to run all kinds of backend site maintenance. The most popular quiz to date? Naming Chemical Compounds, of course – the first one I wrote for my school blog so many years ago, which has had over 48,000 hits since August 1st.

I can’t thank you enough for all of your help finding and reporting bugs so I can fix them while also requesting features and suggesting new quizzes so that I can make the site better. If you’re new to, here are some quick and easy things you can also do to help make the site more popular:

I hope you’re all staying safe and healthy! We went back to face-to-face “hybrid” teaching today after temporarily going fully remote in early December, so with covid cases back on the rise due to the holidays, I’ve started wearing a KN95 mask under my cloth mask, and it was surprisingly comfortable compared to breathing through the PM2.5 carbon filters I inserted into my cloth masks for the first four months. They’re just so expensive – US$2 each in a 20 pack! – so if you have any hot tips for cheaper KN95’s, I’m all ears. Please feel free to drop me a line at any time at or by using the Contact form. Take care!


Bugs are great in ecosystems, but not on

Hello again!  I hope you’re all doing well and staying safe.  I know that most if not all of you have started back to school, whether it’s remote learning, “hybrid” or face-to-face, so I’m sure this has been a stressful time for all of us as we re-learn science teaching during the pandemic.

At my school, we just finished our third week of hybrid or “blended” learning, and the experience so far has been… interesting.  Because I see some students on Tuesday/Thursday, some on Wednesday/Friday, and some that are remote only, I have ten seating charts and fifteen rosters for five classes, so just keeping track of who’s supposed to be in which class on what day has been an adjustment.  Add in students who are sick and more who are quarantined (like our entire football team for 10 days!), and I’m just hoping that my students learn anything this school year without going crazy.  For those of you going back to face-to-face teaching soon, my main recommendation is that you should expect everything you do to take at least three times as long as it normally does, so do less, if possible.

Because of that, I haven’t been able to do much with, except when I finally got caught up with my schoolwork this week, which was just in time for a MAJOR bug involving assignment email notifications!  A few of you wrote me and said your students were getting inundated with dozens and dozens of notifications, sometimes for assignments they’d already completed and sometimes for assignments that weren’t meant for them.  I’m terribly sorry that happened – I know that my kids (both my biological children and my students) are getting slammed right now with email notifications from Google Classroom, Remind, FlipGrid, you name it – so I’ve fixed that bug, along with another one that created duplicate accounts when students used a Registration code.  It turns out that spelling is important, not only in real life, but in programming as well! ??‍♂️

Thanks to your feedback, I’ve also fixed a number of other bugs:

  • students could not retake quizzes even when the assignment was set to allow them to retake
  • teachers couldn’t update student passwords
  • student names were not sorting properly in the Dashboard > Users page due to capitalization issues
  • any student answer with neptunium in the Nuclear Reactions Quiz was marked as wrong, even it was correct (that was a weird one!)

I’ve also been told that some students are not receiving registration emails, either because their district blocks it or the email went to their Spam folder, so I wanted to let everyone know that I wrote lots of documentation for the website, including how to reset a student password.  However, you’re welcome to have students contact me, either by filling out the Contact form or by emailing me directly at, and I will gladly take care of their password issues for you.

There’s good news besides bug fixes.  Several of you have asked me to be able to filter and sort your Quiz Results and your Users list, so I was able to add those features today.  You can sort some columns by clicking on the header of that table, and you can filter results by class, student or assignment by using the dropdown menus.  I hope this helps you keep track of your students’ progress a little more easily!  The sorting feature involves JavaScript, which I’m really not good with, so if you’re having any issues with it, let me know.

If you feel is useful for your students, please continue to tell other teachers about the site!  If you’re on Twitter, please consider following me at @ChemQuizDotNet.  I haven’t had the time to tweet much lately, but I hope to share tips and tricks for using the site in the near future.

One last fun fact: the most popular quiz on the site this past week was the Significant Figures Quiz, with over 5,000 visits!

Sig Figs are popular on but not in Chemistry class

This makes sense since sig figs are such an important fundamental concept in Chemistry (that every Chemistry student hates until they take a college lab course and finally understand why some numbers matters and others don’t).

Thanks again for all of your patience and support as I iron out the bugs and try to make easier to use for teachers and their students.  I appreciate all of the feedback I’ve received so far, so please feel free to email me at if you’re having any issues or if you have an idea for a new feature or quiz.  Good luck this upcoming week, and stay safe!