Christmas CSI Mystery Worksheets

Inside the case file

December is when Christmas addition and subtraction CSI math worksheets earn their keep, and Help! Santa's Sleigh gives them a crime scene. This Christmas CSI Mystery Detective case runs on two-digit and three-digit addition and subtraction with regrouping, plus a taste of multiplication, wrapped in a North Pole mystery for 2nd grade and 3rd grade. Helpers on double shifts, a record year for good children, and days before Christmas somebody at the Pole sabotaged the sleigh. Each correct answer strikes a suspect off the line-up until one remains, from a trail of presents to a decoration colored by the right product. Print in color or black and white, answer keys included, no prep.

The Case: Help! Santa's Sleigh

It has been another long year at the North Pole, and a record number of children have somehow managed to stay good the whole way through. The helpers have been working double shifts to keep up. And now, days out, something has happened to the sleigh. Somebody at the Pole is responsible, and your students have to work out which one before the whole thing is called off.

What's Inside

• Addition along a trail of presents where the running total settles the clue
• Reading letters off a map with a key to decode a message
• Three-digit addition decoded through a letter key
• A matching page where the line drawn passes through the letter that matters
• Multiplication used to color the correct decoration and arrow forward
• 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 is a printable investigation your class solves with math. It runs like a math escape room with the locks taken out - no app, no boxes, nothing to prepare - and instead of opening something, every correct answer rules one suspect out of the line-up until a single name is left. That is the difference between detective activities and ordinary math worksheets: the arithmetic decides the outcome, so students check their own work first. As a math activity it fills a lesson, a center, or a sub plan.

When to Use This Resource

• The last weeks of December, when a normal worksheet will not hold them
• Christmas parties and the days either side of them
• Math centers, early finishers and independent work
• Emergency sub plans that run themselves
• Whole-class detective sessions, small groups or partner work

Grade Levels

Built for 2nd grade and 3rd grade. Second graders usually pair up on the three-digit addition; third graders run the case independently. It also suits 4th grade students who need addition and subtraction review in a form that does not look like going back a year.

Why Teachers Love CSI Mystery Detective Cases

• Zero prep - print and hand out
• Self-checking by design, because a wrong answer breaks the deduction
• A December activity that still does real math
• Works as a whole lesson, a center, or a filler for an awkward afternoon

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