Summer Addition & Subtraction CSI Mystery Worksheets

Inside the case file

Summer CSI math worksheets for 3 digit addition and subtraction with regrouping, wrapped in a CSI Mystery Detective case for June and July. The mystery is Who Stole Summer: the vacation, the beach days and the pool afternoons vanished overnight, and your 2nd grade, 3rd grade and 4th grade students have to work out who took them. Subtraction with regrouping from 100, three digit addition with regrouping and addition and subtraction word problems each fill in one more detail about the culprit, until only one suspect fits. Every page comes in color and black-and-white with answer keys, so it is no prep for summer school in July or a June addition and subtraction review.

The Case: Who Stole Summer?

Summer is gone. The vacation, the beach days, the long afternoons at the pool with friends - all of it vanished overnight, and nobody at home can explain it. There is only one thing left to do: take the case. Your students work the clues one at a time, and every correct answer fills in another detail about the culprit - what they look like, how old they are, and which season they love most. Get the math right and the description narrows until only one suspect can have done it.

What's Inside

• Subtraction from 100 with two-digit numbers, checked against a right-or-wrong tally
• 3-digit addition with regrouping, decoded through a letter key
• 3-digit plus single-digit addition solved by matching each problem to its answer
• A running addition trail where the final total decides the answer through odd and even
• Addition and subtraction word problems set in everyday summer situations
• 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 escape-room-style activity that runs on math instead of padlocks. Each page hands your students a question about the villain and a set of problems that answer it. They solve, they cross suspects off, and the case closes when one name is left standing. The deduction gives the practice a point - students check their own work carefully, because a careless answer sends the whole investigation the wrong way.

When to Use This Resource

• End of year review, when attention is thin and the work still has to happen
• Summer school and holiday review packets
• 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

Grade Levels

Built for 2nd grade, 3rd grade and 4th grade. Second graders find the 3-digit addition with regrouping a genuine stretch and often work it in pairs; third and fourth graders can usually run the case on their own. It also gives 5th grade students who need addition and subtraction review something 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
• Repeatable practice students ask to do again
• Works as a whole lesson, a center, or a filler for an awkward afternoon

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