3-Digit Addition with Regrouping

Inside the case file

Valentines Day 3 digit addition with regrouping math activities for 2nd grade and 3rd grade: five math sheets, each a Mystery Detective page. Print and go, no prep, full answer keys, for February math centers, morning work, early finishers, homework and sub plans. A dinner nobody will claim, a secret gift on the desk and flowers with not a word from anyone carry the week, a correct sum crosses a suspect off the lineup and a wrong one crosses off nobody, so the carrying across the tens and hundreds is real practice on every CSI Mini Mystery Detective page.

This one earns its place in February and then keeps working, because the addition is the point and the valentines are the setting. Students add their way to whoever left the flowers, the marking is student-led, and one CSI Mini Mystery Detective math case a day covers the week of the party with nothing to prepare.

The Cases

1. Valentines Dinner Surprise - a dinner nobody will claim
2. Valentines Gift - a secret gift on the desk
3. Showing Mindfulness - quiet good deeds around the school
4. Valentines Day Card - a card with no signature
5. Valentine Flowers - flowers and not a word from anyone

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 across the tens and the hundreds on most problems
• 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 one printed page holding one crime and one lineup. Every suspect carries a number, the questions on the crime sheet produce those numbers, and a correct answer takes that suspect out until a single name is left. Nothing is cut, laminated or charged, so the arithmetic does all the work, and that is what separates these detective activities from ordinary math worksheets. A case fits one class period.

When to Use This Resource

February needs math that survives a week of cards and candy, and this set does that while still being real three digit practice. Use it in the run up to Valentines Day and again in March, when carrying quietly starts to slip. Because a dropped carry puts the wrong name in the frame, students go back and check the column instead of assuming they were right.

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

Grade Levels

Written for 2nd grade and 3rd grade, where three digit addition with regrouping sits in the standards. Fourth graders take it as a February refresher, and second graders manage it once two digit carrying is secure.

Why Teachers Love These Cases

• Real three digit carrying practice, with a February theme over it
• Students recheck their own columns when the wrong suspect goes
• No prep, and the answer keys make grading quick
• Works with a whole class, a small group, partners, or one student alone

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