A circle is a shape consisting of all points in a plane that are a given distance from a given point. An arc is a curved line that is part of the circumference of the circle.

Kool Circle Facts:
• A straight line from the center of a circle to the edge is called the radius.
• A straight line that passes from one side of a circle to the other through the center is called the diameter.
• The distance around the outside of a circle is called the circumference.
• All points on the edge of a circle are the same distance to the center.
• The value of Pi (π) to 2 decimal places is 3.14, it comes in handy when working out the circumference and area of a circle.
• The circumference of a circle can be found with the following formula: Circumference = π d
• The area of a circle can be found with the following formula: Area = π r²
• An arc is part of the circumference of a circle.
• A chord is a straight line joining two points on a circle, the diameter is an example of a chord (the longest possible one).
• A segment is the region between a chord and the arc it joins.
• A tangent is a straight line that touches a single point of a circle.
• A sector is the region between an arc and two radii.
• The full arc of a circle measures 360 degrees.
• A semicircle is a shape that forms half a circle, the arc of a semicircle measures 180 degrees.
• Circles have a high level of symmetry.
• A circle has the shortest perimeter of all shapes with the same area.
Circle Games:

Crop circles game

Circle the cat Circle game

20 Circle math games for all levels

Pinwheel Circle game

Circle radius and diameter math game

Circle Solver

Pi!

Moving in a Circle Game (PK)

Shape Games

Math Games

Free Presentations in PowerPoint format