Your class will use a set scale to convert diameters of planets to the model size, the diagram given to expand on the number of planets drawn as concentric circles, and examine the scale that would be needed to fit the larger planets on a page.  The out-of-this-world activity is can be used to examine the planets, math scales, and ratios. You could expand on this with astronomy topics, but the worksheet also goes on to practice more scales used in the area of blueprints and architecture