Multiplying Decimals CSI Mystery Worksheets

Inside the case file

Halloween zombie apocalypse CSI math worksheets on multiplying decimals, built for October and the week when the outbreak reaches the classroom. One of the things outside used to be someone your students knew, and this CSI Mystery Detective multiplication mystery for 5th grade and 6th grade identifies it through the numbers it left behind. Students multiply decimals, work multi digit multiplication, and add and subtract large numbers, and every correct answer crosses one suspect off the line-up until a single description fits. Full color and black-and-white pages with answer keys, ready to print and hand straight to desks. They also color the right arrow forward and draw a line through the letter that matters.

The Case: Zombie Apocalypse

The outbreak started at school and finished it. Friends, family and teachers have all gone the same way, and the survivors are barricaded into what is left of the building. One of the things outside used to be someone your students knew. Identifying which one means working the decimals it left behind - how big it is, what it was, how long it has been out there - until only one description fits.

What's Inside

• Multiplying decimals, with answers running into the thousands
• Multi-digit multiplication used to color the correct arrow forward
• A matching page where the line drawn passes through the letter that matters
• Addition with large multi-digit numbers
• Addition and subtraction along a path where the final total settles the clue
• Full color and black-and-white versions of every page
• Answer keys for the whole case

What Is a CSI Mystery Detective Case?

Every CSI Mystery Detective case runs on the same engine: solve, eliminate, repeat. The class is handed a crime and a page of math worksheets, and the answers cross suspects off one by one until a single name remains. It is a math escape room without locks, apps or preparation of any kind. Because the deduction only closes on correct arithmetic, detective activities get checked by the student rather than by you. As a math activity it fills a lesson, sits in math centers, or runs itself as a sub plan.

When to Use This Resource

• Decimal review before or after a unit test
• Halloween week in October, when a normal worksheet will not hold 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
• Whole-class detective sessions, small groups or partner work

Grade Levels

Built for 5th grade, and it carries into 6th and 7th grade for students who need decimal and multiplication review. Fourth graders who have already met decimals can manage it with support, usually working in pairs on the multiplication pages. It also gives older students who are behind on decimal place value something to work on that does not look like remedial work.

Why Teachers Love CSI Mystery Detective Cases

• Zero prep - print and hand out
• Self-checking by design, because a wrong answer breaks the deduction
• Decimal practice students will actually finish
• Works as a whole lesson, a center, or a filler for an awkward afternoon

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