CBSE Class 3 · Mathematics
Toy Joy
Official NCERT chapter from Maths Mela (book code cemm1). ExamMaster notes are original teaching at CBSE Class 3 depth.
This lesson follows the official chapter “Toy Joy” in Maths Mela. The words below are ExamMaster’s teaching, not a paste from the book. Use the NCERT chapter for the classroom sequence; use these notes to hold the idea without copying exercises or figures.
- CBSE Class 3
- Easy level
- 8 concepts
1A box can wear a pig face and still be a cube
Paint or a pig face is a costume. The solid is what you feel: six square faces that meet at edges.
The costume does not add a face. Peel the story; keep the feel-test.
Figure. A pig face is paint on one square. The net still has six matching square faces, so the solid is a cube. Peel the costume; keep the feel-test.
How it works
- Ignore the painted faceCover it if you must.
- Count square facesA cube has six.
- Keep the school nameCube, not pig.
2A bottle can wear a bird face and still be a cylinder
A cylinder has two matching round ends and a curved side. A bird sticker does not change those ends.
Name the solid by the ends and the roll, not by the sticker.
Figure. A bottle with a bird sticker is still a cylinder: two matching ends and a curved side you can roll. The sticker is a costume. It does not add a face or change the ends.
How it works
- Find the two endsMatching circles.
- Feel the curved sideWraps around.
- Keep cylinderThe bird is paint.
3Name the solid by faces you can feel
Hands first. Flat faces, curved faces, how they meet. The school name comes after the feel-test.
A picture from one side is not the feel-test.
Figure. Hands first: count flat faces and feel for a curve. The school name comes after that test, not from a picture or a sticker.
How it works
- Close a viewUse hands, not only eyes.
- Name face kindsFlat square, or curved.
- Then pin the school nameCube, cuboid, cylinder, sphere.
4Edges and corners of the box
An edge is where two faces meet. A corner is where edges meet. You can run a finger along each.
A painted line that is not a meeting of faces is not an edge.
Figure. An edge is where two faces meet. A corner is where edges meet. A painted line that does not sit at a meeting of faces is not an edge.
How it works
- Find two faces that meetThat seam is an edge.
- Find where edges meetThat point is a corner.
- Count only thoseCostume lines do not count.
5Roll, slide, or stack as a test
A sphere rolls every way. A cube slides on a face and stacks. A cylinder rolls on its side and stands on an end.
The motion is evidence. Colour is not.
Figure. A ball rolls every way. A cube slides on a face and stacks. A can rolls on its side and stands on an end. Colour is not evidence; the motion is.
How it works
- Pick one motionRoll, slide, or stack.
- Try it on a tableWatch what happens.
- Group the same moversSame motion, same sort.
6Same solid, different painted face
Two cubes with different stickers are still the same solid. The paint changed; the faces did not.
Sort by the solid, then enjoy the paint as extra.
Figure. Two cubes with different stickers are still the same solid. Run the feel-test; if the faces match, the school name stays cube. Enjoy the paint as extra.
How it works
- Run the feel-testFaces and motion.
- If the test matchesSame solid.
- Leave paint out of the namePaint is not a face.
7A view is not the whole toy
From above, a cube can look like a square. That view is one face, not the six-face solid.
Turn the toy or feel the hidden faces before you name it.
Figure. From above, a cube can look like one square. That view is one face, not the six-face solid. Turn the toy or feel the hidden faces before you name it.
How it works
- Take one viewAdmit it is only one side.
- Turn or feelFind hidden faces.
- Then name the solidNot from a single stamp.
8Keep the school name after the feel-test
Cube, cuboid, cylinder, sphere are names you earn after the test. “Cute toy” is not a solid name.
If you cannot say which test you ran, you do not yet have the name.
Figure. Cube, cuboid, cylinder, sphere are names you earn after a feel-test. “Cute toy” is not a solid name. If you cannot say which test you ran, you do not yet have the name.
How it works
- Run one honest testFaces, or motion.
- Match a school nameThe one the test fits.
- Keep it even if the paint is newPaint does not rename.
A cube with a tiger face drawn on it is still a
- Cube
- Tiger
- Cylinder
Paint is a costume. The six square faces stay.
Notes
- The official chapter title is “Toy Joy”. Teach the school test for that title, not a contest shortcut.
- If a step needs a later class, stop. The next official chapter will pick it up.
Recap
Hold these pegs from the official chapter “Toy Joy”. The wording is ExamMaster’s teaching, not a textbook recap.
- A box can wear a pig face and still be a cube
- Paint or a pig face is a costume. The solid is what you feel: six square faces that meet at edges.
- A bottle can wear a bird face and still be a cylinder
- A cylinder has two matching round ends and a curved side.
- Name the solid by faces you can feel
- Hands first. Flat faces, curved faces, how they meet. The school name comes after the feel-test.
- Edges and corners of the box
- An edge is where two faces meet. A corner is where edges meet. You can run a finger along each.
- Roll, slide, or stack as a test
- A sphere rolls every way. A cube slides on a face and stacks. A cylinder rolls on its side and stands on an end.
- Same solid, different painted face
- Two cubes with different stickers are still the same solid.
Practise Toy Joy
Reading is free and needs no account. Practice, mocks and progress live in the app.
- A 4-question practice set that ends the chapter
- 1 quick check with worked explanations
- Timed mocks scored with the real marking scheme
- Readiness tracked per topic, kept on your device