In which circle did you write triangular prism and rectangular pyramid? Shapes with rectangular faces Shapes with triangular faces A B Shapes with both rectangular and triangular faces Diagram (3) from the book. The two circles overlap, and the overlap is for shapes with both kinds of face.

Both of them go in the middle part, where the two circles overlap . Triangular prism — 3 rectangles on its sides and 2 triangles at its ends. It has both kinds of face. Rectangular pyramid — a rectangle at the base and 4 triangles going up to the top point. It too has both kinds of face. Why it happens: The overlap of two circles is for shapes that belong to both groups. Both these solids have rectangular faces and triangular faces, so neither fits in one circle alone.

Using circles like those on the previous page, can you sort shapes into the categories “Shapes with curved faces” and “Shapes with flat faces”? Shapes with curved faces Shapes with flat faces A B Two circles like the ones on the previous page, ready to be filled in.

Yes. Draw two circles that cross each other, and use the middle part for solids that have both kinds of face. Curved faces only Both curved and flat Flat faces only sphere cylinder (1 curved face + 2 flat circles) cube, cuboid cone (1 curved face + 1 flat circle) triangular prism, hexagonal prism triangular pyramid, square pyramid Why it happens: The sphere is the only solid here that is curved everywhere. A cylinder and a cone are curved on the side but flat at the ends, so they belong to both groups and must sit in the middle.

Build these models with the cubes from the Jaadui Pitara Kit or any other similar material. A. B. C. D. The four models A, B, C and D that are to be built with cubes.

Build every model from the bottom layer upwards . First lay down all the cubes that touch the table. That is the bottom layer. Then put the next layer on top, matching the picture cube by cube. Keep going until the top cube is placed. Now walk round your model and compare it with the picture from every side. What each model looks like A — a solid block of cubes with one step cut into the front. B — a long row of cubes with a raised step at one end. C — a stepped pile: a wide layer at the bottom, smaller layers above. D — a stepped tower of four layers, each layer smaller than the one below. Why it happens: Cubes cannot float. Every cube needs a cube or the table under it, so the bottom layer must be laid first.

NCERT Solutions for Class 4th Maths Chapter 1 Sorting shapes again, Build with Cubes and Cube Towers — In-text Questions

Book page 7 Updated on2026-09-19

Q1.

In which circle did you write triangular prism and rectangular pyramid?

Diagram (3) from the book. The two circles overlap, and the overlap is for shapes with both kinds of face.

Answer

Both of them go in the middle part, where the two circles overlap.

Triangular prism — 3 rectangles on its sides and 2 triangles at its ends. It has both kinds of face.
Rectangular pyramid — a rectangle at the base and 4 triangles going up to the top point. It too has both kinds of face.

Why it happens: The overlap of two circles is for shapes that belong to both groups. Both these solids have rectangular faces and triangular faces, so neither fits in one circle alone.

Q2.

Using circles like those on the previous page, can you sort shapes into the categories “Shapes with curved faces” and “Shapes with flat faces”?

Two circles like the ones on the previous page, ready to be filled in.

Answer

Yes. Draw two circles that cross each other, and use the middle part for solids that have both kinds of face.

Curved faces only	Both curved and flat	Flat faces only
sphere	cylinder (1 curved face + 2 flat circles)	cube, cuboid
	cone (1 curved face + 1 flat circle)	triangular prism, hexagonal prism
		triangular pyramid, square pyramid

Why it happens: The sphere is the only solid here that is curved everywhere. A cylinder and a cone are curved on the side but flat at the ends, so they belong to both groups and must sit in the middle.

Q3.

Build these models with the cubes from the Jaadui Pitara Kit or any other similar material.

The four models A, B, C and D that are to be built with cubes.

Answer

Build every model from the bottom layer upwards.

First lay down all the cubes that touch the table. That is the bottom layer.
Then put the next layer on top, matching the picture cube by cube.
Keep going until the top cube is placed.
Now walk round your model and compare it with the picture from every side.

What each model looks like

A — a solid block of cubes with one step cut into the front.
B — a long row of cubes with a raised step at one end.
C — a stepped pile: a wide layer at the bottom, smaller layers above.
D — a stepped tower of four layers, each layer smaller than the one below.

Why it happens: Cubes cannot float. Every cube needs a cube or the table under it, so the bottom layer must be laid first.

Q4.

How many cubes are there in each of these cube towers?

The two cube towers printed in the book.

Answer

Count layer by layer and add. Do not forget the cubes hidden at the back — they are there, but the picture cannot show them.

The stepped tower (the four-coloured one). Each layer is a square:

Top layer = 1 × 1 = 1 cube
Next layer = 2 × 2 = 4 cubes
Next layer = 3 × 3 = 9 cubes
Bottom layer = 4 × 4 = 16 cubes
Total = 1 + 4 + 9 + 16 = 30 cubes

The cross-shaped tower (the blue one) is much more crowded, and many of its cubes are hidden behind the ones in front. The safe way is to build it and count: lay the bottom layer first and count it, then the next layer, and add the layers up, just as we did above.

Check it yourself: Build the stepped tower with 30 cubes. Take the top cube off and the tower still stands; take a bottom cube out and the whole tower falls.

Why it happens: Adding layer by layer means no cube is counted twice and no hidden cube is left out.

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