The 6th grade students had just finished working on rates and ratios and a lot of fraction work, and had taken an image and increased it by a scale of 3. I was to teach them the next lesson that brought about the idea of different scale factors, and the relationship between the area and perimeter and how they are changed by the scale factor. Students were given what I thought to be a type 1 lesson. Here is the Student worksheet that I made for students to go through. We went through the first 3 shapes as a group.
The troubles I encountered:
- Students didn’t realize and resisted the idea that going diagonally across a square in the grid was not the same length as the height or width.
- Students had trouble understanding that the scale factor was given, and thought I was giving the dimensions of the shape.
- Students had trouble seeing the height of triangles. For some reason the diagonal side threw them off, because they were accurately able to count the height when the diagonal side was covered up. Oddly enough the width was not a problem.
- The students did not remember what the area or the perimeter were, and therefore found them inaccurately.
- Students did not actually look at the scale factor while determining the relationship between the perimeter differences and the area differences.
- Students seemed to have had very little experience working with investigatory types of projects like this, so they were very vocal about being confused before even reading through the directions to see what was asked of them.
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