Area & Perimeter CSI Mystery Worksheets | Grades 3–6 | Geometry Wars

CSI Mystery Detective meets area and perimeter in this April geometry case, with CSI math worksheets on the perimeter of compound shapes, missing side lengths and the area of larger shapes. Pitched at 3rd grade, 4th grade and 5th grade, it is an area and perimeter mystery that also does the job as 4th grade math review. Color and black-and-white versions are both included, with answer keys for every page, so there is nothing to prepare. A key that opens something nobody will name has vanished from the academy. Students check answers for errors, work backwards from a known perimeter and follow a color-the-arrow trail, ruling out a suspect with each clue.

The Case: The Key

There is a key that opens something nobody will name, and it has gone missing from the academy. Nobody saw it go. What is left behind is a set of measurements - the size of the space it sat in, the shape of the mount it came off - and the only way to identify the key is to work them out. Get the area and perimeter right and the description assembles itself.

What's Inside

• Checking area and perimeter answers for errors and tallying which are correct
• Calculating the perimeter of rectangles and compound shapes
• Working backwards from a known perimeter to find a missing side length
• Calculating the area of shapes, including larger multi-digit answers
• A color-the-arrow trail through area problems to reach the final clue
• Full color and black-and-white versions of every page
• Answer keys for the whole case

What Is a CSI Mystery Detective Case?

A CSI Mystery Detective case turns a page of math into evidence. Students solve, and each correct answer removes one suspect from the line-up until a single name is left holding it. There is nothing to unlock, download or prepare - it is a math escape room made of paper. Detective activities also police themselves, which ordinary math worksheets never do: an error leaves a culprit nobody can arrest, so the class rechecks. A math activity that carries a lesson, a center rotation, or a sub plan.

When to Use This Resource

• Area and perimeter review before or after a geometry unit
• A May geometry week, when you want something with a story attached
• 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 need support on the missing-side pages and pair up for them; fourth and fifth graders run the case independently. It also gives 6th grade students who need area and perimeter review 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
• Geometry practice with a purpose behind every calculation
• Works as a whole lesson, a center, or a filler for an awkward afternoon

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