Khan Academy
Khan Academy: Praxis Core Math: Circles Lesson
A basic review of circles and how to calculate the circumference, radius, diameter, and area. Includes practice questions.
BBC
Bbc: Circumference and Area of a Circle
This is where you can pick up some valuable pointers on how to find the circumference and area of a circle. There is also information on how to find the perimeter and area of a semicircle. When you finish working your way through the...
Other
Ic Teachers: Shapes, Circles (Basic)
This basic website will give you lots of information about circles. There are also some questions to test your circle knowledge.
Quia
Ixl Learning: Circumference of Circles
Brush up on your math skills relating to the circumference of circles of measurement then try some practice problems to test your understanding.
Quia
Ixl Learning: Area of Circles
Brush up on your math skills relating to the area of circles then try some practice problems to test your understanding.