Given the dimensions of an object, produce a scale drawing. Given a scale drawing of an object, how big is the original? Relate scale drawings to area. For example: Polygon Q is polygon P, drawn at a scale of 1/2. Polygon Q has what fraction of the area of polygon P? Use these questions to help your students discover how scale factor relates to area and surface area.

Watch these Khan Academy videos:

Do these Khan Academy exercises:

Next, give your students these challenges:

- Gathering Gems by NRICH
- More Pebbles by NRICH

Two Squared by NRICH: Here's the solution to the last problem:

The minimum number of cuts is 3. There are two possible solutions. You can either cut 1 hexagon into 3 pieces, as pictured on the left, or cut 3 hexagons in half, as pictured on the right:

Conclude by leading this investigation:

Tetracide (percentages, algorithm)

by MathPickle

7.G.A.1: Solve problems involving scale drawings of geometric figures, including computing actual lengths and areas from a scale drawing and reproducing a scale drawing at a different scale.