Scale drawings
A map, a floor plan and a model all show something at a different size. How can the same shape be bigger or smaller, and how do you read real lengths off the drawing?
Where you are 2 inside
What this area is about
A logo on a poster and on a badge must look like the same logo. Adding the same length to every side distorts the shape; multiplying every length by the same positive number keeps it, as long as the angles stay the same. That one number, and the scale printed on maps and plans, are what this area is about.
How these fit together
The definition. Scale factor: a figure B is a scale copy of a figure A when every length in B is k times the matching length in A, for one positive number k, and every angle matches. A k greater than 1 enlarges and a k between 0 and 1 shrinks.
The procedure. Using a scale on maps, plans and models reads a stated scale, such as 1 inch to 25 miles, as a rate, and uses it to go from a length on the drawing to the real length or back.
A path through it
Scale factor comes first, then reading maps and plans.
Finish here and scale factor on lengths, perimeters and areas of scaled figures, slope triangles and dilations build on it.