Oval facts for kids

This oval, with only one axis of symmetry, resembles a chicken egg.

An oval is a closed shape that looks a bit like an egg. The word "oval" comes from the Latin word ovum, which means "egg". While we often use "oval" to mean any egg-like shape, in math and technical drawing, it can have a more exact meaning. An oval can have one or two lines of symmetry. The 3D version of an oval is called an ovoid.

What is an Oval?

When we talk about ovals in geometry, the word isn't always super clear. Many different curves are called ovals or are said to be "oval-shaped." Generally, an oval is a smooth, closed shape that looks like an egg or an ellipse.

Here are some common things about ovals:

• They are smooth, simple (they don't cross themselves), and closed shapes.
• Their shape is quite similar to an ellipse.
• An oval usually has a line of symmetry, but not always.

Some examples of shapes that are called ovals include:

• Cassini ovals
• Cartesian ovals
• Superellipses
• Stadium shapes (like a running track)

An ovoid is a 3D shape. You can imagine making an ovoid by spinning an oval shape around one of its lines of symmetry. If something is ovoidal or ovate, it means it has an egg-like shape.

The Shape of an Egg

The actual shape of a chicken egg is a good example of an oval. It's like combining the longer part of a stretched sphere (called a prolate spheroid) with a slightly flattened sphere (called an oblate ellipsoid). These two parts join together smoothly around the middle, and they share a main line of rotation.

Even though "egg-shaped" usually means it's not perfectly symmetrical if you cut it across the middle, it can also describe shapes that are true stretched spheres. It can also refer to the 2D shape that, when spun around its longest line, creates the 3D egg surface.

Ovals in Technical Drawing

An oval with two lines of symmetry made from four curved parts (top). Below, a blue oval is compared to a red ellipse of the same size.

In technical drawing, an oval is a shape made from four curved parts (called arcs). These arcs have two different sizes of radii. The arcs are joined together very smoothly, so you can't tell where one ends and the next begins.

The main difference between an oval made this way and an ellipse is that in an ellipse, the curve's radius changes smoothly all the time. In this type of oval, each part of the curve has a constant radius.

Ovals in Everyday Talk

In everyday language, "oval" simply means a shape that looks like an egg or an ellipse. This can be a flat 2D shape or a solid 3D object.

Sometimes, people use "oval" to describe a shape that looks like two half-circles joined by a rectangle. Think of a speed skating rink or an athletics track. However, the correct name for this shape is a stadium. It can also sometimes mean any rectangle with rounded corners.

In Australia, an "oval" can also be a sports ground for Australian Rules football, like the Adelaide Oval.

A speed skating rink is often called an oval.

People sometimes use the words "ellipse" and "oblong" to mean the same thing as "oval," even though they are not exactly the same in math.

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See also

In Spanish: Óvalo para niños