3D shapes, faces, edges and vertices, and a cube net: 2nd grade and 3rd grade geometry in one CSI Mystery Detective case, ready for March. These math worksheets have students naming solid shapes, sorting 2D from 3D and counting faces, edges and vertices while working a mystery where every witness is truthful and useless, and each correct answer crosses one suspect off the line-up. Few geometry packs end this way: the final page is a cube net to color, cut and fold into the culprit, so the answer stands on the desk. Color and black-and-white versions, answer keys, and the only prep is scissors for that last page.
The Case: The Geometry Investigation
There is a shape at the center of this and the witness statements are, as usual, technically accurate and no help at all. Your students work through it in stages: decode the message, build a suspect list from the shape names, work out that whatever did it has three dimensions, and narrow it down from there until only one shape can possibly fit.
What's Inside
- A letter-and-number cipher that decodes the opening message
- Listing and drawing as many shapes as your students can name
- A word search that builds the suspect list - circle, cone, cube, cuboid, cylinder and the rest
- Shading the three-dimensional shapes to separate them from the flat ones
- A final puzzle that decides between the last two suspects
- A cube net to color, cut and fold into a character
- Full color and black-and-white versions of every page, and answer keys
What Is a CSI Mystery Detective Case?
Every CSI Mystery Detective case is an elimination rather than a test. Students solve a page of math worksheets, each correct answer rules a suspect out, and the last name standing is the culprit. It is a math escape room without locks, apps or preparation. That structure is what makes detective activities self-checking - a wrong answer leaves too many suspects alive and the class can see it at once. Use it as a whole math activity, in math centers, or as something to leave a substitute.
When to Use This Resource
- Introducing or consolidating 3D shapes and their properties
- Nets and shape-building work with a reason behind it
- 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 2nd grade and 3rd grade. Second graders usually need help with the net at the end; third graders manage the whole investigation on their own. It also suits 1st grade students who know their shape names and are ready for something with more steps in it.
Why Teachers Love CSI Mystery Detective Cases
- Almost no prep - print, and the last page needs scissors
- Self-checking by design, because an early error shows up later
- Shape work students will actually finish, and something to take home
- Works as a whole lesson, a center, or a filler for an awkward afternoon
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