4-Digit Addition with Regrouping

Inside the case file

4 digit addition with regrouping worksheets for 3rd grade and 4th grade: five St Patricks Day Mystery Detective math case files, carrying across four columns on every page. March math activities, no prep, full answer keys, then math centers, early finishers, homework, morning work and sub plans, print and go. The leprechaun's gold has gone, an invitation arrived unsigned and somebody is singing Irish lullabies; every total matches one suspect only and crosses them off the lineup, so a CSI Mini Mystery Detective does its own marking.

Carrying across four columns in March is an easy sell with a pot of stolen gold at the end of it. Students add, match the total to a name and cross it off, and the page marks itself as they go. One CSI Mini Mystery Detective math case a day covers St Patricks week.

The Cases

1. Leprechauns Gold - the gold is gone from the pot
2. St Patricks Invitation - an invitation with no sender
3. Surprise Shamrock - nobody will claim it
4. Singing Irish Lullabies - a lullaby with no singer in sight
5. St Patrick Spirit - good deeds all over the school

What's Inside

• Five case files, each with a crime sheet and its own lineup of suspects
• Four digit addition with regrouping on every page
• Carrying across four columns, so the practice goes past three digit work
• 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 hands your class a crime and a lineup of suspects, and the way through it is the math. Work the crime sheet, match each answer to the suspect wearing that number, cross that name off, and keep going until one suspect has not been ruled out. Because the elimination depends on the arithmetic being right, these detective activities catch errors a page of math worksheets would let through. One case takes a class period.

When to Use This Resource

Use this once three digit carrying is solid and the class is ready for the extra column, which for most rooms is late in the year. March gives you the seasonal reason to hand it out, and the skill keeps it useful long after the shamrocks come down. A carry missed in the thousands column strikes the wrong suspect, so students go back and check rather than moving on.

Teachers use it for test prep, homework, math centers, morning work, early finishers, sub plans and homeschool lessons, with a class, a small group or one student.

Grade Levels

Written for 3rd grade and 4th grade, where four digit addition sits in the standards. Fifth graders take it as a quick refresher, and second graders manage it once three digit carrying is secure.

Why Teachers Love These Cases

• Four columns of carrying, a real step up from three digit work
• Students catch a missed carry when the wrong name comes off the lineup
• 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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