2-Digit Subtraction with Regrouping

Inside the case file

St Patricks Day 2 digit subtraction with regrouping worksheets for 1st grade and 2nd grade: five short math sheets, each a Mystery Detective page. Print and go with full answer keys, no prep, for math centers, morning work, early finishers, homework and sub plans through March. Green chocolates with no name, a pot of gold and a teacher under the leprechaun hat carry the cases, each answer crosses a suspect off the lineup until the culprit is left, and the borrowing underneath is the practice a young class needs, one CSI Mini Mystery Detective page a day.

Short cases are what make this work with a young class: a six year old gets to the end of the page and the name, and one CSI Mini Mystery Detective math case fits a morning work slot in St Patricks week. Student-led marking too: the lineup tells them how they are doing, and a quick glance at the key does the rest.

The Cases

1. St Patricks Chocolates - a green box and no name
2. St Patricks Kindness - somebody is doing good all day
3. Pot of Gold at Rainbow - somebody found it first
4. Singing Irish Songs - who is singing in the hallway
5. Leprechaun Dress Up - one teacher is under the hat

What's Inside

• Five case files, each with a crime sheet and its own lineup of suspects
• Two digit subtraction with regrouping on every page
• Borrowing needed on most problems, not just a few
• 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

March, and the week of St Patricks Day in particular, when borrowing is still shaky and the class is in no mood for a plain page of subtraction. Five short cases give you enough for the whole week rather than one lesson. A child who takes the smaller digit from the bigger one out of habit will strike off the wrong suspect and find out straight away, which is the moment that fixes it.

It works for 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 1st grade and 2nd grade, where two digit subtraction with regrouping sits in the standards. Third graders take it as a March refresher, and first graders manage it once subtracting without borrowing is secure.

Why Teachers Love These Cases

• Catches the habit of subtracting the smaller digit from the larger one
• Students see the mistake themselves when the wrong suspect comes off
• Five cases, so the set lasts the whole week of St Patricks Day
• Works with a whole class, a small group, partners, or one student alone

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