CBSE Class 4 · Mathematics
Shapes Around Us
Official NCERT chapter from Math-Mela (book code demm1). ExamMaster notes are original teaching at CBSE Class 4 depth.
This lesson follows the official chapter “Shapes Around Us” in Math-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 4
- Easy level
- 8 concepts
1A city trip is a hunt for solids you can name
A street is a hunt only if you name the solid you can feel or walk around: cube, cuboid, cylinder, cone, sphere.
A pretty building photo is not a name until you run a feel- or view-test.
Figure. A city trip is a hunt only after a test: box to cuboid, tin to cylinder, dice to cube, ball to sphere. Each tile is the school name, not a 3-D drawing. A ball is not drawn as a circle.
How it works
- Pick one objectTank, tin, ball, box.
- Run one testFaces, or motion.
- Pin a school nameOnly after the test.
2Cube, cuboid, cylinder, cone, sphere by feel
Cube: six square faces. Cuboid: six rectangular faces. Cylinder: two matching round ends. Cone: one round end and a point. Sphere: round every way.
Paint does not add a face.
Figure. Hands first: cube has six square faces; cuboid has six rectangular faces; cylinder has two matching ends; cone has one end and a point; sphere rolls every way. Paint does not add a face. Round solids are named by the feel-test, not drawn as circles.
How it works
- Hands firstFaces and ends.
- Match one school nameThe test that fits.
- Ignore the shop stickerA costume is not a face.
3Faces, edges, and corners you can count
A face is a flat (or the curved side you name). An edge is where two faces meet. A corner is where edges meet.
A painted stripe that is not a meeting of faces is not an edge.
Figure. On a cube you can count: 6 faces, 12 edges, 8 corners. An edge is a meeting of faces. A painted stripe that is not a meeting is not an edge. Bar length is the count.
How it works
- Find facesFlat or named curve.
- Find meetingsThose seams are edges.
- Find edge-meetingsThose points are corners.
4A view from the street is not the whole building
From the front, a cuboid can look like a rectangle. Hidden faces still belong to the solid.
Name it after a walk-around or a second view, not one stamp.
Figure. From the street a cuboid can look like one rectangle. Front, side, and top still belong to the solid. Name it after a second view, not after one stamp.
How it works
- Take one viewAdmit it is one side.
- Find a hidden faceSide or top.
- Then keep the solid nameNot “it is a rectangle”.
5Same solid, different size
A small cube and a large cube share the six-square test. Size changed; the name did not.
Bigger is not a new school name.
Figure. A large cube and a small cube share the six-square test. Linear size is 2 to 1, and the drawn sides keep that ratio. Bigger is not a new school name.
How it works
- Run the face-testSame name?
- Allow a new sizeBigger or smaller.
- Keep the school nameCube stays cube.
6Roll, slide, or stack as a test
A sphere rolls every way. A cube slides and stacks. A cylinder rolls on its side and stands on an end. A cone rolls in a circle on its side.
Motion is evidence. Colour is not.
Figure. Motion is the test. Sphere and a cylinder on its side roll; a cone rolls in a circle. Cube and cuboid slide and stack. Colour is not evidence.
How it works
- Pick one motionRoll, slide, or stack.
- Try itTable or floor.
- Group the same moversSame motion, same sort.
7A net is the skin unfolded
A net is the faces laid flat so they can fold back into the solid. A random set of shapes that cannot fold without a gap is not that solid’s net.
Count the faces in the net. A cube-net needs six squares that can meet.
Figure. A cube-net is six equal squares joined so they can fold without a gap or overlap. These six squares are drawn as visual squares (side in x is side in y divided by the 1.6 aspect). A random set of six shapes is not a net.
How it works
- Name the solidCube or cuboid.
- Unfold in your mindEvery face once.
- Check they can fold without overlapThat drawing is a net.
Cube net face-count
A drawing shows 6 equal squares joined so they can fold into a box. Is that enough to call it a cube-net?
- Faces needed6 squares
- Join testMust fold with no gap
- NameA cube-net only if both pass
Pro tip. Six loose squares that cannot fold together are not a net.
8Keep the school name after the test
Cube, cuboid, cylinder, cone, sphere are names you earn. “Nice tower” is not a solid name.
If you cannot say which test you ran, you do not yet have the name.
Figure. Run one honest test, then keep the school name. Cube is earned by six squares. Pretty tower is not a solid name. Paint does not rename.
How it works
- Run one honest testFaces, net, or motion.
- Match a school nameThe one the test fits.
- Keep it if the paint is newPaint does not rename.
A street-front rectangle might be
- One view of a cuboid, not the whole solid
- Proof it is a sphere
- A net of six squares
A view is not the hidden faces.
Notes
- The official chapter title is “Shapes Around Us”. 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 “Shapes Around Us”. The wording is ExamMaster’s teaching, not a textbook recap.
- A city trip is a hunt for solids you can name
- A street is a hunt only if you name the solid you can feel or walk around: cube, cuboid, cylinder, cone, sphere.
- Cube, cuboid, cylinder, cone, sphere by feel
- Cube: six square faces. Cuboid: six rectangular faces. Cylinder: two matching round ends. Cone: one round end and a point. Sphere: round every way.
- Faces, edges, and corners you can count
- A face is a flat (or the curved side you name).
- A view from the street is not the whole building
- From the front, a cuboid can look like a rectangle.
- Same solid, different size
- A small cube and a large cube share the six-square test.
- Roll, slide, or stack as a test
- A sphere rolls every way. A cube slides and stacks. A cylinder rolls on its side and stands on an end. A cone rolls in a circle on its side.
Practise Shapes Around Us
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