Adding & Subtracting Integers CSI Math Mystery Worksheets | Grades 6–8 | The Bank Heist

Students crack a locked-vault case using nothing but positive and negative numbers — adding a negative, subtracting a negative, and answers that land either side of zero — and every solved clue rules out more of the fifteen cash bags until only the stolen one is left. No prep, printable and self-checking, it works for middle school math centers, spiral review, test prep, sub days and independent practice.

Quick Details

Skill: Adding and subtracting integers, positive and negative numbers · Grades: 6–8 · Format: One full case, 5 clue pages + complete answer keys (printable PDF, color and black-and-white) · Theme: The Bank Heist

The Case

Just after closing time on Friday the manager of City Central Bank locked the vault for the weekend. On Monday morning the door was still locked and the alarm had never sounded — but one of the cash bags is gone. Fifteen bags are listed in the register, and only the math will say which one.

The 5 Clues

Clue One — The Coded Message — Students work through a set of integer problems and use the key to decode a hidden message, letter by letter.

Clue Two — Grey or Green? — Every answer is already filled in and students tick only the ones that are right; the bigger tally reveals the color of the bag.

Clue Three — Canvas or Velvet? — Students draw a line from each question to its answer, and the line passes through the number and letter that give the clue.

Clue Four — Small or Large? — A chain of questions leads to one final number, and odd or even decides the size of the bag.

Clue Five — The Number Maze — Students color the path matching each answer, follow it to the next problem, and the last box gives the bag number.

Why Teachers Love It

Zero prep — print and teach. Signs are where integer work falls apart, and because each page is self-checking a dropped negative visibly breaks the puzzle, so students catch it themselves before they ever reach the key. The detective hook holds middle schoolers who would stall on a page of naked integer practice.

Skills Covered

Adding integers with unlike signs where the answer can land either side of zero, subtracting a larger number from a smaller one, adding a negative, subtracting a negative, and judging whether a given integer answer is correct — plus logical reasoning and deductive elimination as students rule suspects out clue by clue.

What's Included

A story page that sets up the case, five printable clue worksheets, the suspect chart of fifteen cash bags, complete answer keys and clear student instructions — every page in full color and in an ink-saving black-and-white version, all in one PDF.

Best Used For

Middle school math centers, warm-ups and bell ringers, homework, early finishers, substitute and relief days, small-group intervention, spiral review and test prep for Grades 6–8.

More From This Line

Browse every CSI Math Mystery, or keep going with Multiply & Divide Integers and Middle School Review.