Summer Addition & Subtraction CSI Mystery Worksheets

Inside the case file

3rd grade and 4th grade 3 digit addition CSI math worksheets, dressed as a back to school and summer review CSI Mystery Detective case that earns a second run in March when addition needs tightening before testing. 4 digit addition is in there too, so it doubles as 4th grade math review. Nothing to prepare beyond pressing print: color and black and white versions, answer keys for every page. The case is The Missing Roller Skates - in the bag last night, gone this morning - and your students have until the rink opens to solve the mystery. Answers pick letters off a map and settle an odd-or-even trail, ruling out a suspect each time.

The Case: The Missing Roller Skates

Your best friend has invited you to the rink and you have not been skating in years. You get dressed, find your bag, and the skates are not in it. They were there last night. Somebody has been through the bag between then and now, and the whole afternoon depends on your students working out who it was before the session starts.

What's Inside

• 3 digit and 4 digit addition, with answers used to pick letters off a map
• A matching page where the line drawn passes through the letter that matters
• Addition decoded through a letter key to reveal the next part of the description
• Addition along a path where an odd or even final total decides the answer
• 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?

Each page asks one question about the thief - the gender, the age, the height, the shoe size - and hands your students the addition that answers it. They solve, they cross a name off the line-up, and the case closes when one suspect is left. A careless answer sends the description the wrong way, so students check their own work properly.

When to Use This Resource

• End of year review in June and July, when attention is thin
• Summer school and holiday review packets
• The first weeks back at school in August and September
• Math centers, early finishers and independent work
• Emergency sub plans that run themselves

Grade Levels

Built for 3rd grade and 4th grade. Third graders usually pair up on the four-digit pages; fourth graders run the whole case independently inside a lesson. It also suits 2nd grade students who are ahead on addition and want something with more thinking in it than extra practice.

Why Teachers Love CSI Mystery Detective Cases

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

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