Rational and Irrational Numbers
Mystery Detective · Grades 7–10 · Bank Vault
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Inside the case file
These rational and irrational numbers worksheets give your 8th grade class ten CSI Mini Mystery Detective math cases on repeating decimals to fractions and on telling rational numbers from irrational ones. Each case takes place in a bank vault, and it's 8.NS.A.1 real number system practice for any point in the unit, from the first lesson to test prep. Use it as a math center, for homework, or as an early finisher activity. It's no prep, and every case has an answer key.
Every repeating decimal is printed with the bar over the repeating digits, the same way your textbook writes it. The rational vs irrational numbers questions mix square roots, π, fractions and decimals, and students have to look at each number in turn. They match every answer to a suspect's badge and cross that suspect off. If the work is right, there's only one suspect left at the end.
What's Inside
- 10 one-page cases with 20 questions each, and an answer key for every case
- On each page, 14 repeating decimals to write as fractions and 6 questions where students pick the rational or the irrational number
- A reference page with worked examples. Put it on the board or give out copies
- Contents page, teacher instructions, a case log and a certificate
- 30 pages, black and white
The Cases
- The Empty Deposit Box - a deposit box emptied with the lock untouched
- The Cloned Keycard - a copied keycard used to get past the guards
- The Silent Alarm - the vault alarm switched off for an hour
- The Frozen Cameras - every vault camera stuck on one picture
- The Stolen Gold Bars - gold bars missing from the lower vault
- The Forged Signature - a withdrawal slip signed in the owner's name
- The Cracked Combination - the vault opened on the first try
- The Midnight Tunnel - a tunnel dug up under the vault floor
- The Vanishing Diamond - a diamond swapped for glass on a tour
- The Inside Job - someone in the bank behind every heist
When to Use This Resource
Start with Case 1 once your class has seen how to turn a repeating decimal into a fraction. The first two cases use one or two repeating digits. After that come repeats that start one place after the decimal point, then three-digit repeats, and the last two cases add numbers greater than one. Terminating and repeating decimals both turn up in the rational and irrational questions, which makes the later cases good for review before a test. The pack also works for small groups, bell ringers, sub days and homeschool, and Algebra 1 teachers can use it to revisit the real number system.
Grade Levels
Made for 8th grade (8.NS.A.1). It's also a quick number system review for 9th graders starting Algebra 1.
Why Teachers Love Mystery Detectives
- No prep. Print the case you need and hand it out
- Students check their own work as they cross off suspects
- Proper bar notation on every repeating decimal
- Repeating decimals to fractions and rational vs irrational practice in the same pack
- Black and white pages that photocopy well
Want more cases like these?
Follow Kiwiland Education to discover more CSI Mini Mystery Detective cases, no-prep math activities, and detective-themed printables for middle school and high school classrooms.
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