3 Dimensional Shapes.

When I teach the volume of three dimensional shapes in geometry, I use a very specific order.  I begin by giving a list of shapes to students so they can research nets on the internet.  They must draw their own nets on paper using a ruler and pencil.  I realize this is old fashioned but they see the number of squares, rectangles, triangles, or circles used to create each 3 dimensional shape.

This is important because this information helps students derive the formulas for volume and surface area.  They use put their nets together so they have the shapes in hand when they derive the formulas.  It makes visualization much easier.

Next I have them work their way through the app Geometry: Volume of Solids Lite.  The app uses videos to explain how to find volume on sphere, cone, cube, cylinder, and pyramid. This reinforces the formula's they derived from the models.

Of course, I give problems to work but I just stumbled across one more thing I can integrate into the topic to add another dimension.  In order to make it work, the students first must know how many edges, faces, and vertex each shape has so they can answer riddles for each shape. I found a slide share site with several riddles or they could make a set of their own.

This would be a great topic to have groups of students create a slide show at the end of the unit.  Each group should include the shape, its net, equations with examples for volume and surface area, real life uses of the shape complete with pictures and a write up, and finish with a riddle.

Its nice for students to find out they need to calculate the surface area of the inside of a rectangular prism (box) in order to buy the correct amount of paint, or find the area of one surface so they can purchase enough flooring for a room. Most of my students are unaware this is the most common use for surface area.

By finding real life uses of volume and surface area, they find a connection between class and the world around them.  Let me know what you think.  I'd love to hear.  Have a great day.

I am trying to get away from using only worksheets so students have a chance