April 2024 newsletter: One-at-a-time mode, colligative properties, excluding ions and more!

Hi everybody, I hope you’re doing well! In this newsletter, I’ve included the following important updates about

  • *NEW* Concentration and colligative properties problems!
  • *NEW* One-at-a-time question mode!
  • *NEW* Exclude specific ions from the Naming Compounds Quiz!
  • Bug fixes and other improvements
  • Site license renewals for 2024-2025 school year

*NEW* One-at-a-time question mode!

Back in December, I received a great suggestion from Malcolm to create a new quiz mode that would only show one question at a time based on feedback he was getting from his students who felt stressed when they saw all of the questions at once. I’ve been teaching for 26 years and have also noticed an increase in anxiety triggers in my own students, so I figured out how to add a new “One question at a time” mode to all of the quizzes on the site!

When you’re creating an assignment, choose this option at the bottom of the form:

Then, when students take the quiz, the questions will look something like this:

The “Grade It!” button only appears on the last question to prevent students from clicking it too early (thanks, Matthew!), but if you activate the “Save progress” option, that button will still show up on every question (thanks, Yvonne!).

Currently, this option is only available to teachers and students at schools with active site licenses. Thanks again to all of the teachers who helped me figure out how to make this new feature happen! I’m hoping that it helps students focus on the problem in front of them instead of worrying about how many they still have left to complete.

*NEW* Concentration & colligative properties problems!

Last month, I started filling in some topical gaps in by adding molecular Lewis structures to the Lewis Dot Structures Quiz. This month, I’ve added colligative properties problems to the renamed Concentrations & Colligative Properties of Solutions Quiz – vapor-pressure lowering (Raoult’s Law), boiling-point elevation and freezing-point depression!

I also added mass percentage, molality, mole fraction (X) and parts per million concentration calculations to the quiz:

To minimize student confusion, I also added an option to lock solvent & solution units to appropriate values based on the problem type:

For example, if you select this option and you’re generating molality problems, all of the solvent values will be in kilograms. Otherwise, the quiz will choose randomly from the solvent units you’ve chosen.

I did my best to test out all of the new problem types, including as multiple choice questions, but if you come across any impossible concentrations, weird bugs or other issues, please let me know. I hope the new colligative property problems and concentration options are useful for you and your students. Thanks to Ken, Andrew, Kelly, Barbara, Abby, Helen, Theresa and all of the teachers who reached out with suggestions on how to improve this quiz!

*NEW* Exclude specific ions!

In last month’s newsletter, I wrote about adding polyatomic ions questions to the Naming Compounds & Calculating Molar Masses Quiz. Shortly after sending that out, I received a fantastic rant from original supporter Ryan about how much he hates mercury ions! 😂 His email made me laugh so hard that I realized I just had to do something about the numerous requests I’ve received over the years to allow teachers to exclude certain ions from that quiz.

My main concern about adding this feature to the quiz was due to the number of options that it already has. The Naming Compounds & Calculating Molar Masses Quiz is by far the most popular quiz on the site, so I didn’t want to add even more options that might confuse users.

To square this circle, I created a new “advanced option” category that only appears for teachers in the Dashboard! Teachers at schools with an active site license can now exclude specific ions from the Naming Compounds & Calculating Molar Masses Quiz by creating a new assignment or editing an existing assignment and checking the boxes next to ions they don’t want to show up for their students:

Thanks also to Bryan, Caytee, Drew, Matthew and all of the other teachers over the years who suggested this feature! I know you’ve been waiting for this for a while, so I appreciate your patience while I figure out (what I hope is) the best way to implement it. Ideas like these have helped me improve over the past four years, so please keep sending them in!

Bug fixes & other improvements

As always, thanks so much to all of the teachers and students who send in bug reports and suggestions for improving! As much as I want the site to be bug-free, there’s so much code that it’s simply impossible – for example, the Dashboard alone has over 10,000 lines of code in three different programming languages. 😱 That’s the reason I keep track of every bug or idea that I receive, because I couldn’t make these improvements without your help and I want to acknowledge everyone’s support. Here are all the updates I’ve made since the last newsletter:

Dashboard – these features and bug fixes also apply to!

  • improvement: allow teachers to limit the number of attempts to a specific number (e.g., 3) instead of just “yes” or “no” (thanks, Yana!)
  • improvement: export results CSV in format for Canvas (thanks, John, Matthew and Malcolm!)
  • bug fix: user accounts created with malformed usernames couldn’t see the Dashboard (thanks, Stephanie!)


  • improvement: updated exam page language for inactive exams
  • bug fix: “Save Progress” button was displaying in exams even when the setting was off (thanks, Yvonne!)

All Quizzes

  • new feature: option for students to see one question at a time (thanks, Malcolm!)
  • improvement: students were accidentally hitting the “Grade It!” button when they meant to go on to the next question in “one at a time” mode, so the button was moved to the last question (thanks, Matthew!)
  • bug fix: word wrap was not working in “one at a time” mode (thanks again, Matthew!)
  • bug fix: “Save Progress” button was not displaying in “one at a time” mode (thanks, Yvonne!)

Acid-Base Equilibrium Quiz

  • bug fix: key was not displaying in printable mode

Balancing, Identifying & Predicting Chemical Equations Quiz

  • improvement: FeCl2 + O2 reaction produces Fe3O4, which is confusing to students, so I removed it from the quiz (thanks, Yvonne!)

Chemical Thermodynamics Quiz

  • bug fix: incorrect values and units for free-energy change were showing up for word problems when solving for standard entropy change (thanks, Rhonda!)

Concentrations & Colligative Properties of Solutions Quiz

  • new feature: added ppm problems (thanks Barbara, Abby, Kelly, Helen and Susan!)
  • new feature: added % mass problems (thanks, Kelly and Andrew!)
  • new feature: added Raoult’s Law and colligative properties problems (thanks, Ken and Andrew!)
  • bug fix: check values for solute and concentration to make sure they’re realistic (thanks, Theresa!)

Lewis Dot Structures Quiz

  • correction: Lewis structure for propyne had too many hydrogens (thanks, Timothy!)
  • correction: lewis structure for GaH3 was incorrect (thanks, Scott!)
  • bug fix: quiz was not grading multiple choice responses for “draw structure” questions (thanks again, Scott!)
  • bug fix: duplicate Group number options were showing up for multiple choice questions (thanks, Danielle!)

Molecular Geometry & VSEPR Quiz

  • polyatomic ions were showing up as polar molecules even if they’re not technically polar (thanks, Chad!)

Naming Compounds & Calculating Molar Masses Quiz

  • new feature: allow teachers to exclude specific ions (thanks, Bryan and Ryan!)
  • improvement: added CH3CO2 and CH3COO as alternative responses in all acetate compounds (thanks, Katharine!)
  • correction: dichromate ion charge was incorrect (thanks, Yvonne!)
  • correction: peroxide ion formula was incorrect (thanks, Brenda!)
  • bug fix: blank answers were being marked as correct for compounds with alternate formulas in the database (thanks, Caytee!)
  • bug fix: nitrite was missing from the list of polyatomic ions to exclude (thanks again, Caytee!)
  • bug fix: when students forget to capitalize elements in polyatomic ion, like Nh instead of NH, it marks it wrong but tells them they forgot to capitalize the “L” (thanks again, Caytee!)
  • bug fix: new “exclude ions” feature was preventing quiz from selecting molecular compounds (thanks, Ryan!)
  • bug fix: IUPAC spellings of “aluminium” and “caesium” were not always accepted as correct answers in compound names (thanks, Danielle!)

Periodic Trends Quiz

  • new feature: added “Additional elements to include” option for Z > 86 (thanks, Mary Ann!)
  • correction: ionic radius for hydrogen was for anion instead of cation (thanks, Scott!)

Stoichiometry & Limiting Reagents Quiz

  • new feature: changed “percent yield” option so that it’s a distinct problem option instead of randomly showing up in problems (thanks, Matthew!)
  • improvement: distractors for percent yield multiple choice problems were often over 100% (thanks again, Matthew!)
  • bug fix: phase change “reactions” from Hess’s Law Quiz were included in problem sets, resulting in strange behavior, so they’re now excluded from problems (thanks again, Matthew!)

Other improvements

  • bug fix: creating users through CSV import wasn’t working due to a backend conflict with WooCommerce and an older version of PHP (thanks, Corey!)

Please keep submitting your bug reports and suggestions! has improved significantly over the past four years because of all the teachers and students who have reached out to me, so thank you all again for your support.

Site license renewals for 2024-2025 school year

It’s renewal time! In the next few weeks, I’m going to start sending out invoices for Dashboard site licenses for the 2024-2025 school year. Like last year, I’ll generate invoices using your most recent payment method; for example, if you purchased a site license with Square, you’ll get an invoice through Square. If you purchased a site license through a school purchase order, I’ll email you an invoice directly as a PDF attachment.

Site licenses are how I pay for web hosting and site security as well as the software I use to write and maintain the quizzes, and it keeps the website ad-free. I understand that financial situations can change from year to year, so if you’ve decided not to renew your Dashboard site license for next school year, just let me know and I’ll make sure you don’t receive an invoice or any reminders. I don’t want to bother any of my fellow educators.

If you’d like to purchase a 12-month site license or renew your existing license, you can do so right now in one of the following ways:

    • credit card through Square (the most popular option)
    • school purchase order (contact me for a sales quote – I’m also happy to fill out any paperwork required by your institution or state)

Additional schools in the same district can purchase an add-on license for 50% off at just US$35 per school. If you also teach physics or you have a colleague who does, you can bundle a site license for the Dashboard for just US$35 more! Please contact me if you have any questions about how to purchase a site license.

Finally, if you teach in a high poverty public school or 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 forever (, too!). I want to be a useful resource for as many students as possible.

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!

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

We just finished our Spring Break in my school district 😭, so while I’m sad that it’s over, that means we have less than eight weeks until the end of the school year! I hope your school year is wrapping up well, and if you have to deal with state-mandated testing like we do in Ohio, I hope it all passes as quickly and painlessly for you and your students as possible.

Thank you again for your continued support of! Please feel free to reach out to me via the Contact form or at if you have any questions, suggestions or concerns. Take care, and good luck with the rest of this school year!