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Fractions math worksheets missing lunchbox detective case cover
CSI Mystery

Fractions CSI Mystery Worksheets

Grades 4–6 · The Case of the Missing Lunchbox

4th grade math5th grade math6th grade mathGrade 4Grade 5Grade 6Answer keys included

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Self-checkingEvery right answer clears a suspect. A wrong answer matches nobody.
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Inside the case file

Simplifying and ordering fractions CSI math worksheets for back to school, delivered as a CSI Mystery Detective case that 4th grade, 5th grade and 6th grade students will race to close. Jonathon Swinston's lunchbox vanished before the bell, hotdog and all, and somebody in the school is eating it. Every fraction answer narrows the suspect line-up: students order fractions from biggest to smallest, simplify to the lowest common denominator, convert improper fractions, and unscramble letters from a key until one name is left. It is a ready-to-print September mystery with color and black-and-white pages and answer keys for the whole case, so the only preparation is the copier.

The Case: The Missing Lunchbox

Jonathon Swinston had been thinking about lunch since the first bell. A chocolate chip cookie, a bag of chips, and a hotdog he was going to heat in the microwave. He had it planned. By the time the bell went the lunchbox was gone from his bag, and Jonathon has taken it about as well as you would expect. Somebody in this school is eating that hotdog.

What's Inside

  • Ordering fractions from biggest to smallest and reading the last one in each set
  • Simplifying fractions to the lowest common denominator
  • Converting improper fractions to proper fractions, then counting odd whole numbers
  • Matching fraction answers to a letter key and unscrambling the result
  • A suspect line-up that narrows every time a clue is solved
  • Full color and black-and-white versions of every page
  • Answer keys for the whole case

What Is a CSI Mystery Detective Case?

It is an investigation on paper: students do the math, and the math names the suspect. Every right answer clears one person from the line-up, and the last one standing is the arrest. A CSI Mystery Detective case behaves like a math escape room with the hardware removed - no locks, no app, no prep. Unlike a stack of math worksheets it cannot be drifted through, because a wrong answer points the description at nobody. It works as a full math activity, in math centers, or as detective activities for early finishers.

When to Use This Resource

  • Fraction review before or after a unit test
  • The first weeks back at school, to see what came back with them
  • Math centers, early finishers and independent work
  • Emergency sub plans that run themselves
  • End of year review, when attention is thin and the work still has to happen

Grade Levels

Built for 4th grade, 5th grade and 6th grade. Fourth graders usually need support on the improper fraction page; fifth and sixth graders run the case independently. It also gives 7th grade students who need a fractions refresher something worth doing.

Why Teachers Love CSI Mystery Detective Cases

  • Zero prep - print and hand out
  • Self-checking by design, because a wrong answer breaks the deduction
  • Fraction practice with a reason to be accurate
  • Works as a whole lesson, a center, or a filler for an awkward afternoon

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