3-Digit Addition with Regrouping

Inside the case file

Halloween zombie math worksheets for 2nd grade and 3rd grade: five Mystery Detective style math cases on 3 digit addition with regrouping. Print and go with full answer keys, no prep, for October math centers, early finishers, homework and sub plans. Zombies take over the school, a classmate is not human, a friend needs saving and a leader needs finding, with carrying across the tens and hundreds on every page; the right sum clears a suspect and the wrong one clears nobody, which is why a class stays on a CSI Mini Mystery Detective to the last sum.

October is when this one earns its keep, the two weeks before Halloween most of all, and a zombie leader to find is why a class works five CSI Mini Mystery Detective math cases of addition with real enthusiasm. Each total points at one suspect, so students check their carrying before they cross anyone off, and the answer keys make the marking quick. Pair it with the zombie subtraction pack.

The Cases

1. Zombies Take Over - find somewhere safe to hide
2. Zombie Classmate - one classmate is not human
3. Save your friend - a friend is lost in the chase
4. Zombie Leader - find who is giving the orders
5. Zombie Teacher - find the cure before the bell

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 more than one column, so it is real regrouping practice
• 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 gives your class a crime, a lineup and a page of questions, and the only route to the culprit runs through the math. Each suspect wears a number, each correct answer matches one of them, and that name is struck off until a single suspect is left. Because a wrong sum rules out the wrong person, these detective activities push students to check their work in a way math worksheets do not. One case fills a class period.

When to Use This Resource

October is when most teachers pull this out, but the five cases run as a story, which makes it just as useful as a week of morning work whenever three digit addition needs keeping alive. Boys who will not touch a worksheet will finish a zombie case, and that is most of the battle. A missed carry names the wrong suspect, so students check their own columns before they hand anything in.

Use it for test prep, homework, math centers, morning work, early finishers, sub plans and homeschool lessons, with a whole class, a small group or one child 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 an October warm up, and second graders manage it once two digit carrying is secure.

Why Teachers Love These Cases

• A story that runs across five cases, so students want the next page
• Students find a missed carry themselves when the wrong name comes off
• 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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