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Tic-Tac-Toe Review Mark as Favorite (36 Favorites)

ACTIVITY in Review, Model of the Atom, Isotopes, Balancing Equations, Atomic Mass, Subatomic Particles, Lewis Dot Diagrams, Electrons, Ions. Last updated January 29, 2024.


In this activity, students collaborate to complete tic-tac-toe review questions to prepare for a test on the atomic structure unit. The idea behind the activity is to give students choice and you can read more about the inspiration for the activity in the May issue of Chemistry Solutions.

Grade Level

Middle School, High School

NGSS Alignment

This lesson will help prepare your students to meet the performance expectations in the following standards:

  • HS-PS1-1: Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.
  • HS-PS1-7: Use mathematical representation to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.


By the end of this lesson, students will have reviewed how to:

  • Balance simple reactions.
  • Count protons, neutrons, electrons for atoms and ions.
  • Be able to calculate average atomic mass given a sample of isotopes.
  • Draw Bohr models and Lewis dot structures for atoms and ions.

Chemistry Topics

This lesson supports students’ understanding of

  • Atomic structure
  • Balancing equations
  • Isotopes
  • Ions
  • Lewis structures
  • Subatomic particles


Teacher Preparation: 15 minutes

Lesson: 30-40 minutes


  • Tic-tac-toe sheets (3)
  • White boards and markers for answers (optional, if making hard copies is not desired)


There are no safety concerns in this activity.

Teacher Notes

  • This is a review activity—make sure the topics covered are not new! I have found this activity to be a poor way to introduce content.
  • Students work in pairs to achieve three in a row (or complete the whole sheet). I give bonus points for the first team to get a tic-tac-toe (or to get all nine answers).
  • When a sheet is done, hand out the next sheet before students can think to say no.
  • I check all the answers from a static location. Students have to get up to see me to get their sheets checked. I put a check next to right answers and circle the number of the “answers that need work.”
  • I hand them the second sheet, same rules for first to achieve tic-tac-toe/solve all 9. Then I give them a third sheet, same rules.
  • The tic-tac-toe boards included in this lesson support the topics listed above, but the same activity could be used to review any concept in a chemistry curriculum.
  • Student pairs MUST turn in at least one sheet checked by me. If they turn in only one sheet, at least six answers must be correct. The third sheet is all extra credit.
  • This could be played non-co-operatively— student A vs. student B in a more classic tic-tac-toe format. I suggest using timers for this to ensure the game moves along. (I have not tried it this way, yet.)
  • Differentiation: Make subsequent sheets more difficult.

For the Student


There are a total of three tic-tac-toe boards to complete. Each one gets subsequently more difficult. This is the first board for students to complete.

How many electrons does Cu1+ have?

Balance the following equation:

____H2 + ____P4 → ____PH3

How many protons does 238U have?
How many neutrons does 107Ag1+ have?

What is the average atomic mass for the following subset of atoms of lithium?

7Li 7Li 7Li 7Li 7Li 7Li 7Li 7Li

7Li 7Li 7Li 7Li 7Li 7Li 7Li 7Li

7Li 7Li 7Li 7Li 7Li 7Li 7Li 7Li

7Li7Li 7Li 7Li 7Li 7Li 7Li 7Li

6Li 6Li

Balance the following equation:

____H2 + ____N2 → ____NH3

Balance the following equation:

____H2 + ____O2→____ H2O

How many electrons does Mg2+ have? How many neutrons does 56Fe3+ have?

This and the other two sheets can be found in the Student Activity document.