1A cylinder has 2 bases
A cylinder has two identical circular bases, one on top and one on the bottom, wrapped together by a curved side surface. Soup cans and paper towel rolls are cylinder-shaped.
2A cone has 1 base and comes to a point
A cone has just one base, and its side surface gathers together into a single point (the apex). The line segment from the apex to the edge of the base is called the slant height. Ice cream cones and party hats are cone-shaped.
3A sphere has no flat faces at all
A sphere is a perfectly round solid where the distance from the center to the surface (the radius) is exactly the same in every direction. Soccer balls and globes are sphere-shaped.
4Unfolding them into nets makes the differences even clearer
Unfold a cylinder and its side becomes a rectangle; unfold a cone and its side becomes a sector (a pie-slice shape). But no matter how you slice up a sphere, there's no way to lay it out flat as a net.
Flattening the Earth (a sphere) into a map inevitably distorts shapes or sizes somewhat, because a sphere simply can't be unfolded completely flat in the first place.
5Try this
- Tap through the three shapes. Compare how the number of bases and the shape of the side surface differ.
- Press the net button. Cylinders and cones show a net, but check what message appears when you select a sphere.
- Spot all three shapes around you. Think of a can, a party hat, and a ball at home, and figure out which solid each one is.