Measurments of Circle and Sphere

Objectives:
Students will understand that the circumference of a circle is a length.
Students will understand that the radius is the factor that changes the circumference and area in a circle and the surface area and volume in a sphere.

1) How does the circumference animation help you to understand that the circumference is a length?
2) What happens to the circumference and area of the circle as the radius increases? as the radius decreases?
3) What happens to the surface area and volume of the sphere as the radius increases? as the radius decreases?
4) At what radius length will the circumference and area of the circle be equal?
5) At what radius length will the surface area and volume of the sphere be equal?

I would use this applet to help students to understand that the circumference isn't just a number, but it is the LENGTH of the outside of the circle. With more time, I would like to make discoveries or models for each of the different measurements so students could discover the actual measurments themselves rather than me just providing them. I would also use it as a tool for students to check their answers for the measurments of a circle and a sphere and see the object they are finding the measurement for.

My main reason for making this applet was to try to make a 3D object or an object that looked 3D in geogebra because we haven't seen that with the ones we have made in class.

Megan Urbanik, 18 November 2013, Created with GeoGebra