{"product_id":"addition-subtraction-csi-math-mystery-worksheets-grades-3-6-the-secret-number","title":"Addition \u0026 Subtraction CSI Math Mystery Worksheets | Grades 3–6 | The Secret Number","description":"\u003cp\u003eA secret two-digit number has slipped away from the crime scene, and your students are the only detectives sharp enough to track it down. This printable \u003cstrong\u003eAddition \u0026amp; Subtraction CSI Math Mystery\u003c\/strong\u003e turns add-and-subtract review into a full investigation, and it's built for \u003cstrong\u003eGrades 3–6 classroom teachers, homeschool parents, and tutors\u003c\/strong\u003e who want focused math practice wrapped in a story students actually care about solving.\u003c\/p\u003e\n\u003cp\u003eStudents work through a series of clue pages, use their answers to eliminate suspects, and race to crack the case — all while getting meaningful practice with addition and subtraction within 100. No apps, no prep, no fuss.\u003c\/p\u003e\n\u003ch3\u003eQuick Details\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eGrade Levels:\u003c\/strong\u003e Grades 3–6 (best for 3rd–5th; works as a 6th-grade warm-up or review)\u003cbr\u003e\n\u003cstrong\u003eFormat:\u003c\/strong\u003e Printable PDF\u003cbr\u003e\n\u003cstrong\u003eResource Type:\u003c\/strong\u003e CSI Math Mystery worksheets\u003cbr\u003e\n\u003cstrong\u003eMath Skills:\u003c\/strong\u003e Addition \u0026amp; subtraction within 100, even and odd numbers, multiples of 3, comparing and sorting numbers\u003cbr\u003e\n\u003cstrong\u003ePages:\u003c\/strong\u003e 9+ pages including answer key\u003cbr\u003e\n\u003cstrong\u003eBest For:\u003c\/strong\u003e Math centers, sub plans, early finishers, review, small groups, and homeschool math\u003cbr\u003e\n\u003cstrong\u003eTech Needed:\u003c\/strong\u003e None — no apps, locks, passwords, or student logins required\u003c\/p\u003e\n\u003ch3\u003eCase Summary\u003c\/h3\u003e\n\u003cp\u003eA number is hiding somewhere between 1 and 100, and it isn't coming quietly. Your students pull on their detective coats, sharpen their pencils, and step up to the crime scene — the only way to identify the culprit is to follow the math.\u003c\/p\u003e\n\u003cp\u003eThe first clue is a coded message. Students crack the cipher one addition fact at a time, and the decoded note hands them their opening lead. From there the evidence stacks up: the suspect is a multiple of 3, it leaves a clear trail across the hundreds chart, and it hides among the even numbers. Each new fact quietly knocks more suspects off the board.\u003c\/p\u003e\n\u003cp\u003eThen it's time to question the witnesses. A full page of addition and subtraction problems gives students the range they need to corner the number — but two suspects still refuse to crack. In the final interrogation, a hundreds-chart color puzzle forces the truth into the open and reveals exactly who did it.\u003c\/p\u003e\n\u003cp\u003eHand your students the evidence, point them at the suspects, and let them prove they can solve the case. The math is the only thing standing between them and the truth.\u003c\/p\u003e\n\u003ch3\u003eSkills Covered\u003c\/h3\u003e\n\u003cp\u003eStudents will practice:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eAdding and subtracting one- and two-digit numbers within 100\u003c\/li\u003e\n  \u003cli\u003eSingle-digit addition with regrouping (code breaking)\u003c\/li\u003e\n  \u003cli\u003eIdentifying even and odd numbers to 100\u003c\/li\u003e\n  \u003cli\u003eIdentifying multiples of 3 and skip counting by 3\u003c\/li\u003e\n  \u003cli\u003eComparing and sorting numbers\u003c\/li\u003e\n  \u003cli\u003eCompleting a hundreds chart\u003c\/li\u003e\n  \u003cli\u003eUsing answers to eliminate suspects\u003c\/li\u003e\n  \u003cli\u003eLogic, reasoning, and problem solving\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eCSI-style math mystery activity\u003c\/li\u003e\n  \u003cli\u003eAddition and subtraction clue pages\u003c\/li\u003e\n  \u003cli\u003eCode-breaker and hundreds-chart puzzles\u003c\/li\u003e\n  \u003cli\u003eSuspect elimination activity\u003c\/li\u003e\n  \u003cli\u003eAnswer key\u003c\/li\u003e\n  \u003cli\u003ePrint-and-go PDF format\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eBest Used For\u003c\/h3\u003e\n\u003cp\u003eThis printable CSI Math Mystery works well for:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eBack-to-school math review (and all-year use)\u003c\/li\u003e\n  \u003cli\u003eMath centers and early finishers\u003c\/li\u003e\n  \u003cli\u003eSubstitute teacher plans\u003c\/li\u003e\n  \u003cli\u003eSmall groups and independent work\u003c\/li\u003e\n  \u003cli\u003eHomeschool math\u003c\/li\u003e\n  \u003cli\u003eEnd-of-unit review\u003c\/li\u003e\n  \u003cli\u003eAddition and subtraction practice and reinforcement\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Kiwiland Education","offers":[{"title":"Default Title","offer_id":61980734390642,"sku":"2671501","price":4.5,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0909\/2848\/0626\/files\/addition-subtraction-csi-math-mystery-grades-3-6-cover.jpg?v=1782474834","url":"https:\/\/kiwilandeducation.com\/products\/addition-subtraction-csi-math-mystery-worksheets-grades-3-6-the-secret-number","provider":"Kiwiland Education","version":"1.0","type":"link"}