Description

Defend the town from a stomping giant with this Geometry Math Mystery 3rd Grade activity! ‘The Case of the Giant Goblin’ is a high-engagement math review that challenges students to master 2D/3D shapes, area, and perimeter to save the day.

It’s the perfect no-prep math activity! This resource is loaded with options, including an optional video hook and a NEW ending video (with voiceovers!) to wrap up the case!

Easy Prep for Print or Digital

This resource is designed to be low-prep for you and high-engagement for your students.

• Printable PDF Version: Just print the worksheets, staple, and go.
• Google Slides Digital Version: 100% paperless! Simply assign in Google Classroom. (Students must be in ‘edit mode’ to type).
• Easel by TPT: Complete the worksheets digitally for seamless online learning.

Geometry Math Mystery 3rd Grade Activity

To banish the Giant Goblin, students must unlock five clues by correctly solving a complete Geometry and Measurement review:

• Clue 1: Identifying Shapes (Recognizing 2D and 3D figures)
• Clue 2: Perimeter (Calculating total distance around shapes)
• Clue 3: Area with Unit Squares (Counting tiles to find area)
• Clue 4: Area Formula (Multiplying Length x Width for rectangles)
• Clue 5: Advanced Perimeter (Finding the Missing Side Length)

Flexible for Any 3rd Grade Classroom

Use this versatile geometry worksheets alternative for:

• A fun end-of-unit assessment
• Math centers or stations
• Homework or enrichment
• Your “early finisher” tub
• A lifesaver for your sub-tub!

Pacing & Timing

This is a comprehensive review that can take anywhere from 30 minutes to 2+ hours, depending on your students’ skill level. We recommend pacing it by one clue at a time.

Common Questions for this 3rd Grade Math Review

Q: Does this cover Area OR Perimeter?
A: It covers **both**! We know students often confuse these two concepts, so we included specific clues for each to help them practice the difference. Clues 2 and 5 focus on Perimeter, while Clues 3 and 4 focus on Area.

Q: Is there a scaffolded approach to Area?
A: Yes. We start with **Unit Squares** (Clue 3) to reinforce the concept of “covering space,” and then move to the **multiplication formula** (Clue 4) for fluency. This ensures deep understanding.

Q: How does differentiation work with these?
A: That’s our secret weapon! Many of our stories are available for other grades, so you can “clue swap” with the 2-6 grade packs. We even have a blog post explaining how: learn how to differentiate here.

Other Grade Editions Available!

Love this ‘Giant Goblin’ theme? This mystery is also available for other grade levels (great for differentiation)!

• 2nd Grade Edition
• 4th Grade Edition
• 5th Grade Edition
• 6th Grade Edition
• 8th Grade Edition 

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A complete answer key and printable awards are included!