Rounding to the Nearest 10 and 100

Inside the case file

Rounding to the nearest 10 and 100 worksheets for 3rd grade and 4th grade, six monster CSI Mini Mystery Detective math cases where every rounded number crosses a suspect off the lineup until one is left. Three cases round to the nearest 10 and three to the nearest 100, so these rounding math activities cover the whole standard and check themselves, because a number rounded the wrong way lands on no suspect. Print and go with full answer keys: no prep math centers, morning work, early finishers, homework and sub plans all year.

Six CSI Mini Mystery Detective math cases is more than most rounding packs give you, which means a full week of practice plus one spare, with the nearest 10 and the nearest 100 kept on separate pages so you can teach one before the other. The monsters keep a third grader on the page, and the lineup tells them when to look again before you have to.

The Cases

1. The Student Monster - something is loose in the school
2. Monster Principal - the principal is not himself today
3. Monster Teacher - extra schoolwork for everybody
4. School Imposter Among Us - something got inside the school
5. Monster Thief - every school book has gone
6. The Teachers Lunch - the lunch disappears before noon

What's Inside

• Six case files, each with a crime sheet and its own lineup of suspects
• Three cases round to the nearest 10 and three round to the nearest 100
• Numbers that sit either side of the halfway point, so the rule gets tested properly
• 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 a single page investigation your class solves with math. The lineup of suspects each carry a number, the crime sheet produces those numbers, and a correct answer removes one suspect until a single name is left holding it. There is no kit, no app and nothing to assemble, so the arithmetic does all the work, which is what makes detective activities stick where math worksheets slide off. One case runs about a class period.

When to Use This Resource

Six cases split across two scopes means you can teach rounding to the nearest 10 one day and the nearest 100 the next without handing out the same page twice. Use it through the rounding unit and again before testing, when students have started rounding to whatever place looks easiest. Rounding to the wrong place crosses off the wrong suspect, so the habit gets caught on the page.

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 alone.

Grade Levels

Written for 3rd grade, where rounding to the nearest 10 and 100 sits in the standards, and used with 4th graders as a warm up before rounding to larger places. Second graders take the nearest 10 cases once place value to 100 is secure.

Why Teachers Love These Cases

• Six cases in one download, split so you can teach the two scopes apart
• Students catch their own rounding slips when the wrong suspect comes off
• No prep, and the answer keys make grading quick
• Works with a whole class, a small group, partners, or one student alone

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