CSI Mystery Detective work for 3rd grade and 4th grade: February CSI math worksheets on ordering numbers least to greatest, 3 digit place value and odd and even numbers. The witnesses agree the number has three digits and is a small one, which still leaves a room full of suspects, so this mystery number case doubles as a 4th grade math review and a winter math activity. Color and black-and-white copies of every page are in the file, so it prints and goes. Students decode the opening cipher, build the line-up from the witness descriptions, sort odd from even and order the numbers from smallest to biggest, sending suspects home until one number is left.
The Case: The Suspect Number
The witnesses are unusually cooperative for once. They are certain the number has three digits, and just as certain that it is a small one. That still leaves a room full of suspects, so your students take it further: odd or even, where it sits in the order, which numbers it lives nearest to. Each answer sends more of them home.
What's Inside
- A letter-and-number cipher that decodes the opening message
- Building the suspect list from three-digit numbers described by the witnesses
- Sorting the suspects into odd and even numbers
- Ordering the line-up from smallest to biggest
- Working out which tens and hundreds each number sits between
- A final shading puzzle that separates the last two suspects
- Full color and black-and-white versions of every page, and answer keys
What Is a CSI Mystery Detective Case?
A CSI Mystery Detective case is a printable investigation your class closes with math. Each correct answer eliminates one candidate, and the case ends when a single one is left. It behaves like a math escape room minus the locks, the app and the setup - you print it and hand it out. What separates detective activities from ordinary math worksheets is that the arithmetic has consequences, so students check their own before handing it in. It carries a whole math activity, a center rotation, or a sub plan.
When to Use This Resource
- Ordering and comparing numbers review before or after a unit test
- Place value work that is not another page of columns
- Math centers, early finishers and independent work
- Emergency sub plans that run themselves
- Back-to-school weeks and end of year review
Grade Levels
Built for 3rd grade, 4th grade and 5th grade. Third graders usually pair up for the line-up page; fourth and fifth graders run the whole investigation independently inside a lesson. It also suits 2nd grade students who are secure with three-digit numbers and want something longer than a worksheet.
Why Teachers Love CSI Mystery Detective Cases
- Zero prep - print and hand out
- Self-checking by design, because an early error shows up later
- Ordering 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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