Solid Detectives
A solid has flat or curved surfaces. An edge joins faces, and a vertex is a corner. A prism has two matching parallel bases; a pyramid has one base and triangular sides meeting at an apex.
Before you try
Before you play, make a prediction: How many vertices does a square pyramid have? Explain what you expect and what part of the model will help you check it.
Try it out
Interactive activity
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What happened?
Move a control to see what changes and why.
The game practises one idea at a time with simple drawn pictures. Check the same idea with real objects and your NCERT textbook (Chapter 1: Shapes Around Us, pages 1–23).
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Try these ideas
- Compare a cube and a triangular prism. Count hidden edges too.
- Try a new puzzle with ↻. Describe what changed and which mathematical rule stayed the same.
- Complete a round, then explain your method before you move to the next one.
Why it works
A solid has flat or curved surfaces. An edge joins faces, and a vertex is a corner. A prism has two matching parallel bases; a pyramid has one base and triangular sides meeting at an apex.
A triangular prism has 5 faces, 9 edges and 6 vertices. Compare a cube and a triangular prism. Count hidden edges too.
Do not count only the edges visible in a drawing. Solids also have hidden edges and faces.
This activity connects to Shapes Around Us, NCERT Class 4 maths, printed pages 1–23. Use the picture or objects to explain each step before relying on a calculation. The game practises one part of the chapter at a time; the other three activities extend the chapter’s ideas.
Worked example: How many faces, edges and vertices does a square pyramid have? Its square base is one face. Four triangular sides meet at the apex. There are 5 faces, 4 base edges + 4 sloping edges = 8 edges, and 4 base vertices + 1 apex = 5 vertices.
Check your understanding
Question 1 of 2
How many vertices does a square pyramid have?
Which solid has two matching triangular bases?
Explain it in your own words
What changed? Why did it happen? Where might you notice this in everyday life?
For parents & teachers
- Try with everyday materials. Compare a cube and a triangular prism. Count hidden edges too. Ask the child to make a new example using paper, counters, household objects or a labelled sketch.
- Listen to the explanation. Do not count only the edges visible in a drawing. Solids also have hidden edges and faces. Ask “How could we check?” and encourage a second representation of the same idea.