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Kiwiland Education

4-Digit Addition with Regrouping | Mystery Detective Worksheets | Grades 2–5 | New Year Theme

$4.00 USD

New Year math worksheets for 2nd grade, 3rd grade and 4th grade: five January cases of 4 digit addition with regrouping, each a CSI Mini Mystery Detective math page. Print and go, full answer keys: no prep math centers, morning work, early finishers, homework and sub plans for the first weeks back. A party popper nobody saw, a secret gift and a countdown heard in an empty room carry the theme, each total crosses a suspect off the lineup until the culprit is left, and carrying across four columns is what gets students there.

The first week of January needs something with a bit of pull, and a New Year party with an invitation for the detective has more pull than a page of sums. Students add, find the suspect with that total and cross the name off, so the class settles into the year without you at the front. All five CSI Mini Mystery Detective math pages are self-marking.

The Cases

  1. Party Popper - a party popper goes off unseen
  2. New Year Gift - a secret gift on the desk
  3. Auld Lang Syne - someone singing where nobody was looking
  4. New Year Countdown - a countdown heard with nobody there
  5. New Year Party - an invitation left for the detective

What's Inside

  • Five case sheets in color, each with its own lineup of suspects
  • The same five cases in black and white for cheaper printing
  • 4 digit addition with regrouping, 16 questions on every sheet
  • Every answer matches one suspect and no other, so the page checks itself
  • A full answer key for all five cases
  • A teacher instruction page and a color in page for early finishers

What Is a CSI Mini Mystery Detective?

A CSI Mini Mystery Detective is a printed case with a lineup of suspects, each carrying a number. The questions on the crime sheet produce those numbers, a correct answer strikes one suspect off, and the last name standing is the culprit. The elimination only works when the math is right, which is what makes these detective activities catch slips that a page of math worksheets would let through. One case fits one class period, with nothing to prepare.

When to Use This Resource

Bring this out in the first week back in January, when the class needs something to settle into and the addition unit picks up where it left off. Four digit addition with regrouping is a skill that wants repetition, and five separate cases give you that without five identical pages. Because a wrong total takes the wrong name off the lineup, students find their own slips before you ever see the sheet.

It covers test prep, homework, math centers, morning work, early finishers, sub plans and homeschool lessons, with a whole class, a small group or one student on their own.

Grade Levels

Written for 2nd grade, 3rd grade and 4th grade, where multi digit addition with regrouping sits in the standards. Fifth graders take it as a quick refresher before larger numbers, and it works as an extension for a confident 1st grader.

Why Teachers Love These Cases

  • Four digit totals, big enough to need regrouping on nearly every question
  • Students check themselves, because the wrong total takes off the wrong name
  • Print and go, and the answer keys make grading quick
  • Color and black and white versions of every case

Love this resource?

Follow Kiwiland Education to discover more CSI Mini Mystery Detective cases, no-prep math activities, and detective-themed printables for elementary classrooms.

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How Math Mysteries Work

Each Math Mystery resource gives you five one-page cases that turn math practice into a clue-based investigation. Here's exactly how a case plays out.

CASE FILE 5 MYSTERIES

Every set is a ready-to-solve investigation

Students become the math detective. They read a story, crunch the numbers, and use their answers as evidence to rule out suspects — until only the culprit is left standing.

1
STEP 01

Read the Case

Each mystery opens with a short, themed story that sets the scene and tells students exactly what they're trying to find out — who took something, what went missing, or what really happened.

Hooks them in seconds
2
STEP 02

Solve the Problems

Students work through a set of problems built around the target skill. Every answer is a clue — so there's a real reason to get each one right.

Focused skill practice
3
STEP 03

Eliminate Suspects

Students match their answers against the suspect list and cross off names one clue at a time. Wrong math means the wrong suspect — so the activity self-checks as they go.

Self-checking built in
4
STEP 04

Crack the Case

One suspect is left — and students reveal who did it. The payoff makes review feel like a win, and they're ready to start the next case.

The satisfying reveal

See it in action

SOLVE A CLUEAnswer = 576
→
MATCH THE ANSWER576 = Bianca
→
CROSS OFFBianca
No apps. No logins. No prep. Just print, hand out, and let them investigate.

New to the format? Read What Is a Math Mystery? for how they work and how to run one in class.

Why Teachers Use Math Mysteries

Skill practice that feels like a case worth solving — and a download that quietly does a lot of your planning for you.

5one-page cases per set
0prep or setup time
color & black-and-white
answer keys included

Five Mysteries in One

Every download includes five separate one-page cases — enough for a full week of practice, a center rotation, or a sub-day backup that's always ready to go.

Truly No-Prep

No cutting, laminating, apps, or logins. Print in full color or black-and-white and hand them straight out — that's the whole setup.

Self-Checking by Design

Students need the right answers to rule out the right suspects, so accuracy matters — and the included answer keys mean no grading for you.

Fits Any Routine

Use one case as a morning warm-up, or spread the five across the week for centers, partner work, early finishers, or intervention.

Keeps Students Hooked

The mystery format gives even reluctant mathematicians a reason to keep solving. Review starts to feel like a game, not another worksheet.

Differentiation-Friendly

Great for on-level practice, an extension for advanced students, or a targeted review pass for anyone who needs another go at the skill.

NO PREP PRINT & GO ANSWER KEYS INCLUDED

What's in every Math Mystery set

5 full-color mysteries 5 black-and-white versions 5 complete answer keys Print-and-go teacher page Bonus coloring page
Practice that feels like a case worth cracking.

Frequently Asked Questions About Math Mysteries

Printable Math Mystery worksheets that turn math practice into clue-based detective investigations.

Is this Math Mystery a digital activity?

No. This is a printable PDF resource. Students complete the Math Mystery on paper. No physical item will be shipped.

Do students need apps, locks, passwords, or logins?

No. Students do not need apps, locks, passwords, or logins. Teachers can print the pages and use the Math Mystery straight away.

How do students solve the Math Mystery?

Each resource includes five one-page cases. In each one, students solve the math problems and use their answers to eliminate suspects until only one remains and the case is cracked.

Can this Math Mystery be used for sub plans?

Yes. Math Mysteries work well for sub plans because students can work through the clues independently, with a partner, or in small groups.

Can this Math Mystery be used for homeschool?

Yes. This printable Math Mystery can be used for homeschool lessons, tutoring, review practice, enrichment, or extra math support.

Will this work for early finishers or math centers?

Yes. Math Mysteries are a good fit for early finishers, math centers, small groups, independent work, review lessons, and extra practice activities.



New years 4-digit addition with regrouping worksheets

4-Digit Addition with Regrouping | Mystery Detective Worksheets | Grades 2–5 | New Year Theme

$4.00

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