Naming and describing solid shapes

When you reach for it

A flat shape lies on paper, like a drawing or a paper cutout. A solid shape is thick: a child can pick it up, turn it over and look at it from every side. Four solids come first, each with a name: the cube, the sphere, the cone and the cylinder. A child describes them by what they do (roll, stack, slide) and by their flat parts, called faces. The flat shapes a child already knows by name turn up again as those faces.

Each day takes about ten to fifteen minutes. Use real things the child can hold; the pictures are for the practice at the end of each day.

Day 1: Flat or solid?

You need: a ball, a box (a tissue box or small block), and a circle and a square cut from paper.

Put the paper circle and the ball side by side. Ask, “How are these the same? How are they different?” Both look round from above. Then let the child pick each one up. The paper circle is so thin it lies flat on the table; the ball fills the hand and can be turned all the way around. Say: “The circle is a flat shape. The ball is a solid shape.” Do the same with the paper square and the box.

Then play “Flat or solid?”: point to things around the room, and the child says which. A picture in a book is flat even when it shows a ball, because the page is flat; the ball itself is solid.

Practice. Point to each picture.

1. Picture A: flat or solid? Answer: flat. It is a circle, shaded like a paper cutout.
2. Picture B: flat or solid? Answer: solid. The curved line around its middle shows a ball, round all the way around.
3. Picture C: flat or solid? Answer: flat. It is a square.
4. Picture D: flat or solid? Answer: solid. You can see its front, its top and its side.
5. A sticker of a star: flat or solid? Answer: flat. It lies flat on the page.

Day 2: Cube, sphere, cone, cylinder

You need: one real object for each solid: a number cube (die) or a square block, a ball, a cone that is closed at the bottom (a cone block from a set of wooden solids, or a party hat with a paper circle taped over its open end), and a can or a glue stick.

Hold up one object at a time, say its name, and have the child say it back.

• A cube is a block with six flat faces, all squares of the same size.
• A sphere is round everywhere, like a ball. It has no flat part at all.
• A cone has one flat circle at the bottom and goes up to a point.
• A cylinder has two flat circles, one at each end, joined by a curved side, like a can.

Then go on a solid shape hunt: “Find something in the room shaped like a cylinder.” A candle, a jar and an oatmeal box are all cylinders. Size and position do not change the name: a tiny die and a big moving box are both cubes, and a cone turned upside down is still a cone. Turn each object over and ask, “Is it still a cone?”

Practice. Name each solid in the picture.

1. Solid A. Answer: a cube. It is small, but all its faces are squares.
2. Solid B. Answer: a cone, standing on its point with its circle on top.
3. Solid C. Answer: a cylinder, lying on its side.
4. Solid D. Answer: a sphere.
5. A basketball and an orange: what solid shape is each? Answer: both are spheres. One is bigger, and that does not change the name.

Day 3: Roll, stack, slide

You need: the four objects from Day 2 and a large book propped up on one end to make a ramp.

Set each solid at the top of the ramp, let go, and ask, “Did it roll or slide?” Then try to stack: “Can you put another block on top of it?” Talk about what you see:

• The sphere rolls whichever way you set it down. Nothing stays on top of it.
• The cylinder rolls when it lies on its side. Stood on a flat end, it slides, and you can stack on its flat top.
• The cone, set on its side, rolls around in a circle about its point. Stood on its flat circle, it slides, but nothing stays on its point.
• The cube never rolls. It slides on any face, and it stacks well.

The flat parts are the reason: a flat face lets a solid slide and lets another solid sit on it, and a curved side lets it roll.

Practice.

1. Which solid rolls whichever way you put it down? Answer: the sphere.
2. Which solid never rolls, but slides and stacks? Answer: the cube.
3. A cylinder is lying on its side on the ramp. Does it roll or slide? Answer: it rolls, along its curved side.
4. Push a cone lying on its side. What does it do? Answer: it rolls around in a circle, turning about its point.
5. Can you build a tower of two cubes? Of two spheres? Answer: two cubes, yes: a flat face sits on a flat face. Two spheres, no: the top one rolls off.

Day 4: Flat faces

You need: a lump of play dough, flattened, and the four objects again.

Show the child the flat part of the cube. Say: “A flat part of a solid is called a face.” Press one face of the cube into the play dough and lift it: a square print. Press the flat end of the cylinder: a circle. The flat bottom of the cone: a circle too. Then press the sphere: it only makes a round dent, never a flat print, because a sphere has no face.

Count faces together while you look: the cube has six, all squares; the cylinder has two circles; the cone has one circle; the sphere has none. Some books later keep the word “face” only for flat parts with straight sides; for now, any flat part of a solid is a face.

Practice. Use the prints in the picture.

1. Print A. Which solid could have made it? Answer: a cube. Its faces are squares.
2. Print B. Which solids could have made it? Answer: a cylinder or a cone. Both have a circle for a face. Not the sphere: it leaves a rounded hollow, not a flat print.
3. Print C is a smaller square. Which solid made it? Answer: a smaller cube. A small cube is still a cube.
4. Which of the four solids can never leave a flat print? Answer: the sphere. It has no flat face.
5. Put one sticker on every face of a cube. How many stickers? Answer: 6.

Exercises

Show the check picture. These two solids have not appeared before.

1. Name solid A and solid B.
2. Which of the two could roll? On which one could you stack a block?

Where this goes next

Faces are only the start. The lines where two faces meet and the corners where those lines come together are the subject of Faces, edges and vertices, and solids whose faces are all flat with straight sides, like the cube, become Polyhedra. Later the cylinder and cone are looked at closely in cylinders and cones, and the sphere in Spheres.