This is a free comparing and equivalent fractions game for 3rd, 4th and 5th grade: a five-minute detective case you put on the board and solve as a class. It practices 3.NF.A.3 (equivalent fractions, compare with the same numerator or denominator) and 4.NF.A.1–2 (equivalence and comparison). There are no logins, no student accounts and nothing to print unless you want the full case afterwards.
Why it works for comparing and equivalent fractions
The badges are fractions, so every clue is a comparison or a simplification: is 6/8 greater than one half? Does 4/12 simplify to 1/3? Is the denominator even? Students have to reason about every badge to clear it, and equivalent fractions hide in every lineup to catch the ones who only look at the numerator.
How to run it
- Put it on the board. Tap Put it on the board above the case and it fills the screen. Six suspects, each wearing a badge number. One of them did it.
- Read clue 1 out loud. The class works out which badges the clue rules out. Tap each suspect it clears; a correct tap stamps them CLEARED, a wrong one just wobbles.
- Clues 2 and 3 unlock as you go. Keep clearing until one suspect is left, then tap them to close the case. The reveal explains every clue.
- Play it again. New lineup keeps the clues and shuffles the suspects. New clues gives you a fresh case. Round 2 and Round 3 are waiting in the tabs.
Three tips from the classroom
- Draw a number line from 0 to 1 and mark one half before you start. Most clues can be checked against it.
- For simplifying clues, ask for the common factor out loud. What goes into both 6 and 8?
- Let a student explain why a badge is cleared using a picture: a bar, a circle or the number line.
Making it easier or harder
For 3rd grade, run the round slowly and build every fraction on a bar. For 5th grade, ask students to order the six badges from least to greatest before the first clue, then see which clue clears the most.
Questions teachers ask
What fractions does it use?
Halves, thirds, quarters, fifths, sixths, eighths, ninths, tenths and twelfths, including equivalent forms like 2/4, 4/8 and 6/12.
Does it cover equivalent fractions?
Yes. Clues include in simplest form the badge is 3/4 and equivalent to one half, so students have to simplify to clear suspects.
Is there a printable version?
The packs below are the printable version on the same standards: a page of fraction problems, a lineup of suspects, every right answer crosses one off. Answer keys included.
