Converting fractions to decimals with tenths and hundredths is the focus of these 4th grade math CSI Mini Mystery Detective worksheets, ten no prep cases with a dinosaur museum theme. They cover decimals back into fractions too, which makes this a full decimal fractions unit. Use these math activities for math centers, morning work, small groups and early finishers. Every case comes with an answer key.
Use this pack after your fractions unit, when your class starts writing decimals. It starts with tenths, like 7/10 = 0.7, and finishes with every kind of question on one page. The zero in 0.06 gets a whole case of its own, with 6/100 and 60/100 side by side. Students match each answer to a suspect and cross that name off, and the pages are self-checking.
What's Inside
- Ten one-page detective cases on tenths and hundredths, each with an answer key
- Fractions to decimals with tenths, hundredths and mixed numbers
- A full case on the zero in numbers like 0.06 and 4.05
- Decimals back to fractions, and equal tenths and hundredths such as 3/10 = 30/100
- Adding tenths and hundredths, written as a fraction and as a decimal
- Two mixed cases that bring every skill together
- A reference page with worked examples for each skill
- A contents page, teacher instructions, a detective case log and a certificate of achievement
- 30 black and white pages, ready to print
The Cases
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The Missing T. Rex Skull - tenths to decimals
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The Cracked Dinosaur Egg - hundredths to decimals
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The Fake Footprints - the zero in hundredths
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The Vanishing Mummy - mixed numbers to decimals
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The Smashed Vase - decimals back to fractions
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The Pharaoh's Mask - equal tenths and hundredths
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The Stolen Diamond - adding tenths and hundredths
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The Switched Painting - adding, answer as a decimal
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The Camera Blackout - fractions and decimals both ways
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The Midnight Roar - fractions and decimals mixed
When to Use This Resource
The cases start with tenths, then hundredths, mixed numbers, decimals back to fractions, and adding. You can hand out one at a time through the unit or pull a single page when a group needs more practice with hundredths. The early cases suit students writing decimals for the first time, and the mixed cases at the end show you who can move between fractions and decimals in either direction. It also works for guided math groups, homework, test prep, sub plans, homeschool lessons, and back to school or end of year review.
Grade Levels
Written for 4th grade, where students first write fractions with denominators of 10 and 100 as decimals. The mixed number and adding cases give confident 4th graders a stretch, and the whole pack makes a quick decimals review at the start of 5th grade.
Why Teachers Love Mystery Detectives
- Nothing to cut or prep
- Self-checking
- Cases that build from tenths to mixed questions
- A dinosaur museum mystery with a T. Rex skull and a pharaoh's mask
- Black and white printable pages
Want more cases like these?
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