Shapes

An arch is a curved, self-supporting shape usually used over doorways or to support old bridges. Arches shift the downwards force at the top of the arch to a sideways force at the bottom of the arch, so there must be a strong wall holding the base of the arch up. Arches work particularly well underground where the earth holds the sideways force. When two arches are put next to each other, the sideways forces are cancelled out, so a row of arches together e.g. under a long bridge only need thin walls or pillars holding the arches up.

The stone at the top center of an arch is usually a slightly different shape, or is more decorative. It is called the keystone.

An arrow is a projectile that is fired from a bow. Arrows have a pointed end that is used to pierce things.

An arrow is also any shape that looks like the arrow projectile. Arrows are used to point somewhere, or tell you which direction to go.

Used as a verb, you bump into something when you hit it, but not especially hard. You might bump your knee on your coffee table if you are walking around your living room in the dark.

As a noun, a bump is a raised, slightly rounded area on something else. The stone pillar in the picture has a lot of bumps carved into it.

A circle is a shape with one long, curved edge that is the same size in all directions. Things that are like a circle are often called round. The circle in this picture is a pot, with a cat asleep in it.

A coil is a word used to describe something that is in loops on top of each other to form a helix or loops around each other to form a spiral.

The photo is of a fire hose coiled into a spiral.

A cone is a shape with a round bottom that gets smaller as it goes until it reaches a point. If you cut a slice through a cone parallel to the bottom, it will be the same shape as the bottom. If you cut a slice through the cone vertically going through the top point, you will get a triangle.

Many things are cone shaped. volcanos tend to be cone-shaped, pinecones and pine trees like the ones in the picture are cone-shaped, and of course traffic cones are cone shaped.

A cross is a shape made by crossing two straight lines. Crosses are often built out of two pieces of wood nailed together. The Christian cross usually seen on top of churches has the horizontal part of the cross much shorter than the vertical part.

A cube is a three dimensional shape that is square on every side. A cube has six sides, or faces. There are many cubes around you every day. Can you see some now?

Something is curled if it goes around in a series of loops, either in a helix or a spiral. The curls in the picture are more of a helix, wheras a fern frond uncurling is more of a spiral.

A curve is a line that bends to one side or the other along its length. The opposite of curved is straight.