Volume of Composite Figures | Mystery Detective Worksheets | Grades 5–7 | Additive Prisms

Additive volume worksheets, volume of composite figures practice, and rectangular prism activities for 5th grade, 6th grade, and 7th grade are all included in this printable Mini Mystery Detective pack of math worksheets. Volume is additive — so students break each compound solid into two non-overlapping rectangular prisms, find the volume of each part, and add the parts together to get the total. Then they match every answer to a suspect's ID badge and cross names off until one villain is left standing. Perfect for math centers, morning work, homework, early finishers, substitute and relief days, indoor recess, geometry and measurement review, spiral review, and test prep. Completely no prep — just print and go.

Two print versions are included. Every mystery comes twice: once with lightly shaded solids that make the 3D shapes pop off the page, and once with plain outline solids for ink-friendly printing. The figures, the numbers, the suspects and the answers are identical in both, so you can hand either version to the same class.

What's Inside

• Finding the additive volume of compound solids built from two non-overlapping rectangular prisms
• Applying V = length x width x height to each prism, then adding the parts to find the total
• Recognizing volume as additive — decomposing a solid into prisms that do not overlap, then adding the parts
• Reading labeled dimensions off clear three-dimensional drawings, in feet and in inches
• Working across a real range of solids — step shapes, L-shaped solids, blocks stacked on a base, and side-by-side prisms of different heights and depths
• Logical reasoning and deductive elimination as students rule suspects out one answer at a time
• Self-checking answer keys for every single case

Five detective cases to crack: The Crate Mix-Up, The Hay Bale Heist, The Pool Plug Puzzle, The Fish Tank Fiasco, and The Gift Box Grab. Answer keys included for every case.

What is a Mini Mystery Detective?

A no-prep detective activity where students solve math problems to cross off suspects and unmask the culprit. Skill practice plus critical thinking in one engaging, self-checking worksheet set — like an escape room without the locks. Get the volume right and exactly one suspect is left standing, so students know straight away whether their working is sound.

When to Use This Resource

• Math centers and small-group rotations
• Morning work and bell ringers
• Early finishers and fast-finisher folders
• Substitute, relief and emergency sub plans
• Homework and independent practice
• Spiral review before a unit test
• Geometry and measurement review
• Indoor recess and end-of-term days
• Small-group intervention and re-teaching

Grade Levels

Designed for 5th, 6th, and 7th graders. Also beneficial for struggling 8th grade students who need extra practice with volume and for advanced 4th graders ready for a challenge.

Why Teachers Love Mystery Detectives

• Zero prep — print and teach
• Self-checking, so students get instant feedback without you marking every page
• The detective hook pulls in reluctant and struggling mathematicians
• Real rigor — students decompose, calculate and reason, not just fill in blanks
• Five separate one-page cases make it easy to differentiate or stretch across a week
• An ink-saver version so a class set does not empty your toner

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