Common Core Math Vocabulary

# Circle - Definition with Examples

**What is a circle? **

A circle is a round shaped figure that has no corners or edges.

In geometry, a circle can be defined as a closed, two-dimensional curved shape.

A few things around us that are circular in shape are a car tire, a wall clock that tells time, and a lollipop.

**Center of a Circle**

The center of a circle is the center point in a circle from which all the distances to the points on the circle are equal. This distance is called the radius of the circle.

Here, point P is the center of the circle.

**Semicircle:**

A semi-circle is half of a circle, formed by cutting a whole circle along a line segment passing through the center of the circle. This line segment is called the diameter of the circle.

**Quarter Circle:**

A quarter circle is a quarter of a circle, formed by splitting a circle into 4 equal parts or a semicircle into 2 equal parts.

A quarter circle is also called a quadrant.

## Let's sing!

*The tires of an old yellow car.*

*The round lid of a candy jar.*

*The clock hanging on the wall.*

*A cat playing with the red ball.*

*The sweet chocolate donut I ate,*

*And a whole apple pie on my plate.*

*The shiny buttons on my dress.*

*What’s the shape? Take a guess.*

*They are all round like a C-I-R-C-L-E.*

## Let's do it!

Instead of handing out geometry worksheets to your children, ask your child to observe/spot the things that are circular in shape, such as a bangle, a door knob, or a hula hoop.

You can also ask your child to pick out a circular object such as Bangle, or a Hula hoop and show/identify the center of the circle in it. Ask them to show you how a semi-circle or a quarter circle can be formed.

## Related math vocabulary

The Complete K-5 Math Learning Program Built for Your Child