3-Digit Addition with Regrouping
Mystery Detective Worksheets · Grades 2–4 · St Patrick's Day
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Inside the case file
St Patricks Day 3 digit addition with regrouping math activities for 2nd grade and 3rd grade: five math activities, Mystery Detective style, carrying across the tens and hundreds throughout. Print and go, no prep, full answer keys, for March math centers, morning work, early finishers, homework and sub plans. A pot of gold found first, Irish songs in the hall and the leprechaun's gold gone from the pot carry the week, the right sum clears a suspect and the wrong one clears nobody, so every CSI Mini Mystery Detective page is real practice that marks itself.
Five separate CSI Mini Mystery Detective math cases give you five days of March practice without repeating a page, and a class adds its way eagerly to the culprit. Self-marking as well: the lineup does the checking, and a glance at the key is all you need.
The Cases
- Pot of Gold at Rainbow - somebody found it first
- Irish Songs - singing in the hall all morning
- Showing Mindfulness - quiet good deeds around the school
- Leprechauns Gold - the gold is gone from the pot
- St Patricks Day Cake - a green cake in the staffroom
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 in more than one column, so students cannot shortcut it
- 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 puts a crime, a lineup and a page of math in front of your class, and the only way to name the culprit is to get the math right. Each suspect carries a number, each solved question matches one of them, and that suspect is crossed off until a single name remains. Because a wrong sum eliminates the wrong person, these detective activities make students check their work in a way math worksheets cannot. One case fills a class period.
When to Use This Resource
March, when three digit carrying was taught back in the fall and half the class has quietly stopped doing it properly. These five cases bring it back in a week of short sessions rather than one long review page. A carry dropped in the tens names the wrong suspect, so students go looking for the column that went wrong instead of asking whether they got it right.
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.
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 March refresher, and second graders manage it once two digit carrying is secure.
Why Teachers Love These Cases
- Brings a fall skill back without it feeling like revision
- Students find their own dropped carries 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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