Volume of Cylinders Cones and Spheres | Mystery Detective Worksheets | Grades 7–9 | Formulas

Volume of cylinders, cones and spheres activities, 8th grade geometry worksheets, and volume formula practice for 7th grade, 8th grade and 9th grade math are all included in this Mini Mystery Detective pack. Students substitute the labeled radius and height into V = πr²h, V = ⅓πr²h and V = 4⁄₃πr³ to find the volume of each solid, then use their answers to eliminate suspects and unmask the villain. Perfect for volume unit review, math centers, morning work, early finishers, sub plans and test prep, and completely no prep - just print and go.

Every radius and height is labeled on the diagram, pi is given as 3.14 on every page, and answers are rounded to the nearest tenth in US customary units - cubic feet and cubic inches.

What's Inside

• Finding the volume of a cylinder from its radius and height using V = πr²h
• Finding the volume of a cone using V = ⅓πr²h, with the perpendicular height marked on every drawing
• Finding the volume of a sphere from its radius using V = 4⁄₃πr³
• Choosing the right formula for the solid in front of you on the mixed review page
• Squaring and cubing a radius, then multiplying by pi in the correct order
• Using 3.14 for pi and rounding a volume to the nearest tenth
• Reading dimensions straight off a labeled diagram - no measuring required
• Recording answers in cubic feet and cubic inches, with the unit on every answer line
• Real-world solids: water tanks, cannery tins, sand piles, ice cream cones, gym balls, weather balloons and fun fair props
• Red-ink answer keys for every case

Seven detective cases to solve: The Water Tank Switch, The Soup Can Swap, The Sand Pile Shift, The Ice Cream Mix-Up, The Gym Ball Bungle, The Balloon Breakout and The Fun Fair Shuffle. Answer keys included for every case.

What is a Mini Mystery Detective?

A Mystery Detective is a print-and-solve detective activity - like a classroom escape room without the locks or the prep. Every answer matches one suspect's ID badge, so each solid a student works out crosses another name off the list. The badge left unmatched at the end belongs to the villain, which makes the page self-checking: if two suspects are still standing, something needs another look. Real skill practice, critical thinking, and a detective hook that keeps the whole class working.

When to Use This Resource

• Volume and geometry unit review
• Math centers and small groups
• Morning work and bell ringers
• Early finishers and enrichment
• Substitute teacher plans
• Homework and spiral review
• State test prep and end-of-year review

Grade Levels

Designed for 7th grade, 8th grade and 9th grade geometry and measurement. Also beneficial for struggling high school students who need extra practice substituting into a volume formula, and advanced 6th graders ready to move beyond rectangular prisms.

Why Teachers Love Mystery Detectives

• Zero prep - print and hand out
• Self-checking, so students catch their own mistakes before you do
• Every solid is drawn and clearly labeled, with the radius and height given
• The value of pi and the rounding rule are printed on every page, so student answers match the key exactly
• Cylinders, cones and spheres each get their own practice pages before the mixed review
• Detective storyline keeps reluctant mathematicians working to the last question
• Works for independent practice, partners, small groups or a whole-class challenge

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