Winter 3 Digit Addition with Regrouping Mystery Detective Activity

Inside the case file

3 digit addition with regrouping winter snow day math worksheets, five Mystery Detective cases for 2nd grade and 3rd grade in one download. Snow day math activities for December to February, then no prep math centers, early finishers, homework and sub plans, print and go with full answer keys. Mittens with no owner, a snowman that appeared overnight and a sled nobody can find carry the cases, the right sum clears a suspect on every page, and carrying across the tens and hundreds throughout means these CSI Mini Mystery Detective pages check themselves.

This is the winter set to keep for the day the plan falls apart, because a class can run it without any explaining from the front. Students add, find the suspect with that total and cross the name off, and a substitute has nothing to teach. Any CSI Mini Mystery Detective math case left over is a math center for the rest of the term.

The Cases

1. Winter Mittens - mittens with nobody to claim them
2. Snowman Surprise - it was not there yesterday
3. Winter Coat - gone on the coldest day
4. Where is the Sled? - nobody can find it anywhere
5. Snow Angel - a snow angel and no footprints

What's Inside

• Five case files, each with a crime sheet and its own lineup of suspects
• Three digit addition with regrouping on every page
• Carrying needed in the tens and the hundreds, so it is not a single step
• Each answer matches one suspect and no other, so the page checks itself
• A full answer key for every case
• Print and go: no cutting, no laminating, nothing to prepare

What Is a CSI Mini Mystery Detective?

A CSI Mini Mystery Detective is a printable case with a lineup of suspects, each carrying a number. The questions on the crime sheet produce those numbers, a correct answer strikes one suspect off, and the last name standing is the culprit. The elimination only works when the math is right, which is what makes these detective activities show up mistakes a page of math worksheets would hide. One case fits one class period, with nothing to prepare.

When to Use This Resource

Winter is a long stretch of short attention, and this is the set that gets three digit addition practiced through it. Use it after the regrouping unit, then again in January when everything taught in November seems to have gone. The page corrects the student rather than the other way round, because a dropped carry puts the wrong name in the frame and they notice before you do.

It carries test prep, homework, math centers, morning work, early finishers, sub plans and homeschool lessons, with a class, a small group or one child alone.

Grade Levels

Written for 2nd grade and 3rd grade, where three digit regrouping sits in the standards. Fourth graders take it as a start of year check, and second graders manage it once two digit carrying is secure.

Why Teachers Love These Cases

• Carrying twice in a sum, which is where second and third graders slip
• Students go back and find the wrong column themselves
• No prep in the middle of winter, when there is no spare time
• Works with a whole class, a small group, partners, or one student alone

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