What are Plane Shapes? - Definition & Examples

Definition of a Plane Shape

When you think of plane shapes, you might think of a big jet flying in the sky, but plane shapes didn't get their name because they fly. They're called plane shapes because they're figures that are flat and closed. That's right! Plane shapes don't pop up or out at you. Instead, plane shapes are what you would see in a drawing or a cartoon, but remember they cannot have any gaps or parts that are open. Sometimes, you may even hear them being called two-dimensional or 2-D shapes. This means that you cannot touch them on all sides like a ball or a block.

Plane shapes can include sides, which are straight lines that make up the shape, and corners, which are where two sides come together. Some examples of plane shapes that you may see every day are stop signs, a sheet of paper, a paper plate, a stamp, or even a tortilla chip. There are many kinds of plane shapes, but we will focus on 5 basic kinds: squares, rectangles, circles, triangles, and octagons.

Square vs. Rectangle

A plane shape that has four sides that are all the same length and has four right angles for corners is called a square. You can see squares in checkerboards, the keys of your keyboard, the side of a Rubik's cube, or in your kitchen tiles. Any time a four-sided shape has equal sides and right angles for corners, that's a square.

A plane shape with four straight sides and four right angles for corners is called a rectangle. The difference between a square and a rectangle is that a rectangle's sides don't have to be the same length. A piece of paper has two long sides and two short sides, so it's a rectangle.