Addition & Subtraction Word Problems Within 1000

Inside the case file

Addition and subtraction word problems within 1000, three-digit story problems, and school-themed math worksheets for 3rd grade are all included in this no-prep Mini Mystery Detective pack. Students solve their way through a page of word problems, use each answer to cross a suspect off the line-up, and the last suspect standing is the culprit — perfect for math centers, morning work, early finishers, substitute and relief days, homework, small-group intervention, and spiral review. Completely no prep — just print and go.

Use it as a 3-digit addition and subtraction review, a problem-solving unit warm-up, a no-prep math sub plan, or a station in your math rotations. Every case mixes joining, separating, part-part-whole and comparing situations — how many altogether, how many are left, how many more and how many fewer — so students practice choosing the operation from the story instead of hunting for key words. It fits 2nd grade extension, 3rd grade core instruction, and 4th grade review or intervention.

What's Inside

• Adding three-digit numbers within 1000 with regrouping: 423 + 250, 359 + 363, 110 + 248
• Subtracting three-digit numbers within 1000 with regrouping: 616 - 346, 833 - 409, 923 - 414
• Comparison word problems that ask how many more and how many fewer, the ones students most often add by mistake
• Choosing the operation from the situation rather than from key words, so problem solving transfers to new wording
• Reading and interpreting real school situations: library books, lunch orders, sports day points, book fair takings and lost property
• Self-checking suspect line-ups, so a student who slips knows straight away that something has gone wrong
• Full answer keys in red for every case

Five school mysteries to crack: the missing library books, the muddled lunch line, the changed sports day score, the missing book fair cash, and the raided lost property pile. Answer keys included for every case.

What is a Mini Mystery Detective?

A no-prep detective activity where students solve math problems to cross off suspects and unmask the culprit. It is like an escape room without the locks — the math has to be right for the elimination to work, so skill practice and critical thinking come in one engaging, self-checking worksheet set.

When to Use This Resource

• Math centers and station rotations
• Morning work and bell ringers
• Early finishers and fast-finisher folders
• Substitute and relief day plans
• Homework and independent practice
• Small-group intervention and re-teaching
• Spiral review and test prep
• Indoor recess and end-of-unit rewards

Grade Levels

Designed for 3rd graders working with addition and subtraction within 1000. Also beneficial for struggling 4th and 5th grade students who need extra problem-solving practice, and for advanced 2nd graders ready to move past three-digit computation into word problems.

Why Teachers Love Mystery Detectives

• Zero prep — print and hand out
• Completely self-checking, so you are not marking every page to know who is on track
• The detective hook pulls in reluctant and struggling mathematicians
• Real-world school situations build genuine problem solving, not key-word guessing
• One page per case makes it easy to assign, differentiate and take in

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