Add & Subtract Unlike Fractions

Inside the case file

Thanksgiving fractions practice for 5th grade: ten CSI Mini Mystery Detective math cases on adding and subtracting fractions with unlike denominators, with mixed numbers on every page. Six cases are straight computation and the other four are fraction word problems about pies, cider and the parade. Give them out as homework or set them up in a math center during November. There's nothing to prep, and you'll find an answer key for each case.

A prize pie has been swapped, the turkey is on the floor, and someone tore the THANK YOU banner in half. Your students are the detectives on every one of these cases. Each fraction they add or subtract with a common denominator crosses one suspect off the list, and a page of mixed numbers starts to feel like a hunt for the culprit. If their answers are right, one name is still standing at the end, and that's the villain.

What Is a CSI Mini Mystery Detective?

It's a short detective case that fits on a single sheet of paper. The problems sit on the left and a list of suspects sits on the right, each one with a fraction next to their name. When a student's answer matches a suspect's fraction, that person is cleared. The case title, the story and the box for the villain's name are all on the same page. All you need is a pencil.

What's Inside

• 10 one-page Thanksgiving cases with 180 problems in all
• Cases 1 to 6 have 20 fraction and mixed number problems each
• Cases 7 to 10 have 15 short word problems each. They're about baking, raking leaves, the hayride and the parade
• An answer key for every case
• Denominators of 2, 3, 4, 5, 6, 8, 10 and 12, and every answer in simplest form
• A Mixed Numbers Guide with one addition and one subtraction worked step by step
• Teacher instructions, a contents page, a Detective's Case Log and a Fraction Detective certificate
• 30 pages, black and white

The Cases

1. The Blue Ribbon Pie Swap - a prize pumpkin pie switched before the bake-off
2. The Corn Maze Mix-Up - the maze signs moved, and a class got lost
3. The Pilgrim Hat Heist - the giant hat missing from a parade float
4. The Spilled Cider Barrel - apple cider tipped over at the farm stand
5. The Secret Stuffing Recipe - Uncle Ray's recipe gone from the kitchen drawer
6. The Toppled Turkey Tray - the roast turkey knocked off its tray before dinner
7. The Hayride Holdup - a hayride wagon stuck at the pumpkin patch gate
8. The Giant Pumpkin Weigh-In - rocks hidden inside the biggest pumpkin at the fair
9. The Whipped Cream Caper - every can of whipped cream empty by noon
10. The Torn Thankful Banner - the school's THANK YOU banner ripped in two

When to Use This Resource

The first six cases are a good fit once your students can find a common denominator. The word problem cases come after that and use the same skills. A single case works as a bell ringer or a small group task, and a few cases left with sub plans will cover the short week before Thanksgiving. Students who still need the steps can keep the Mixed Numbers Guide beside them. You can also use the pack for intervention, test prep or homeschool lessons.

Grade Levels

Written for 5th grade. It practices 5.NF.A.1, adding and subtracting fractions and mixed numbers with unlike denominators, and 5.NF.A.2, the word problems that go with it. 6th grade teachers can use it as a fraction review.

Why Teachers Love Mystery Detectives

The steps never change from one Mystery Detective pack to the next. Students solve each problem, find the matching suspect, cross that suspect off and write the villain's name in the box. Each case is complete on its own page. That means you can use them in order or choose just the ones you want, and checking a page against its key is quick.

Want more cases like these?

Follow Kiwiland Education to discover more CSI Mini Mystery Detective cases, no-prep math activities, and detective-themed printables for elementary classrooms.

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