First, students will gain an intuition of dilating lines by playing with this Geogebra interactive. Here's a video which might help you figure out what questions to ask, to guide your students on their discovery. Then students will learn how to dilate lines.
One type of problem, is to provide two lines, then ask for a center and scale factor that would map one of the lines onto the other.
Dilating lines by Khan Academy
Another type of problem, is to provide the equation of a line, in slope-intercept form, the center of dilation, and the scale factor. From here, the task is to find the equation of the dilated line. Here's a video on that.
2.5 Dilating Lines by Benjamin Siegel
Next, give your students these challenges:
- 2020 Math Kangaroo Levels 7-8 Problem #29 by STEM4all
Transformations on a Pegboard by NRICH: For the first part of this challenge, we can move any of the pegs to make the right triangle.
Conclude by leading this investigation:
Pollinator Puzzles (multiplication, division)