Multiplication & Division CSI Mystery Worksheets
Grades 3–5 · Alien Invasion
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Inside the case file
3rd grade and 4th grade math review drives these Alien Invasion CSI math worksheets: multiplication facts, rounding to the nearest ten and multi-digit addition in one CSI Mystery Detective case. It slots into January as winter math activities to get the class back into gear. The invaders read our digital numbers faster than we do, so the last defense is math worked by hand until it names the alien in charge. Both color and black-and-white versions are included, and the only prep is the printer. Students check answers, crack a code chart and trace the right path, ruling out a suspect per correct answer until the mystery ends on one alien, answer keys included.
The Case: Alien Invasion
It was only ever a matter of time before they arrived, and our own technology made it easy for them. Every digital system we built runs on numbers, and the invaders learned to read them faster than we did. Now the only defence left is the one thing they did not expect anyone to still do by hand: work the math out properly, on paper, and use it to find the one alien behind the whole operation.
What's Inside
- Checking answers for errors and tallying the results to settle a clue
- Multi-step problems where the last answer unlocks a code chart
- Addition with three-digit and four-digit numbers
- Rounding to the nearest ten, shading the correct answer to reveal letters
- Multiplication facts used to trace the right path to 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?
Your students get a crime, a line-up and a page of math worksheets - nothing else. The answers do the eliminating: one correct answer, one suspect gone, until only the culprit is left. That is a CSI Mystery Detective case, and it works like a math escape room without the locks or the login. It also marks itself, which a practice page never does, because a wrong answer leaves a description matching nobody. Run it as a whole math activity, in math centers, or as detective activities for early finishers.
When to Use This Resource
- Spiral math review across multiplication, addition and rounding in one sitting
- Back-to-school weeks, to see what came back with them
- Math centers, early finishers and independent work
- Emergency sub plans that run themselves
- End of year review, when attention is thin and the work still has to happen
Grade Levels
Built for 3rd grade and 4th grade. Third graders will find the four-digit addition a stretch and often pair up for it; fourth graders can usually run the whole case on their own. It also gives 5th grade students who need multiplication and rounding 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
- Several math skills reviewed in one activity rather than one skill drilled
- Works as a whole lesson, a center, or a filler for an awkward afternoon
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