Monday, March 26, 2012

Cylinders

Along the same lines as surface area and volume of rectangular prisms, I went with the net approach for the surface area and volume of cylinders. I think it really allowed the students to see the connection between the circumference and the length of the rectangle as well as the connection between the height and the width being the same distance.
{what you cannot see here is the 2nd circle, which has been taped down to the note page. Before we developed the formula, we talked about the cylinder being made of two circles and a rectangle. To develop the surface area formula we talked about need the area formula for a circle twice as there are two circles and then the area of the rectangle, which could be obtained from the circumference multiplied by the height}
Similar to the discovery of the volume of a rectangular prism being the area of the top multiplied by the number of 'layers,' the students discovered that the volume of a cylinder is simply the area of the circle multiplied by the number of 'layers.'

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