Thursday, 25 November 2010 | 1 Comment
I like teaching surface area, I think it’s an interesting topic. Yet, I find kids struggle with the concept. Not understanding the basics of area and then getting over the prior knowledge of solids meaning volume are two aspects that cause some difficulty.
This is how I break down surface area for my low ability Year 8 class.
Concepts: counting the faces of the centicubes rather than counting the cubes, reinforced by creating multiple solids with different surface areas using the same number of cubes, understand what is meant by a 3 × 2 × 2 rectangular prism.
Layed out in “Making Solids: Investigation” (Page 1 of download below). This is based on an activity in the book Access to Stage 5.1 Maths.
Concepts: calculating area by counting squares, see that a rectangular prism is made up of six rectangles (3 pairs of congruent rectangles).
Make net (Page 3 of download below). Print to card, and cut in half (no tabs on these nets, I use sticky tape to hold together).
Similar to 2., but this time students draw their own net. Concepts: the drawing of a net from an image of a solid, understand how the edges of the rectangles join.
Draw nets – Page 4 of download below.
Concepts: determine which lengths are used for each face and that faces have a matching face so the area of a face can be doubled.
Concepts: understand how a triangular prism is constructed from two triangles and 3 rectangles, understand how the side lengths of the triangles relate to the side lengths of the rectangles, see the common side length of all the rectangles.
Use: Paper Model of a Triangular Prism
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Simon Job — eleventh year of teaching maths in a public high school in Western Sydney, Australia.
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