Visualizing Mathematics

I am creating a lesson for Middle School students on Visualizing Mathematics. I want to use this lesson at the beginning of the school year to understand how my student's view the subject of Mathematics and to get them thinking outside of the box about how Math is all around them in the real world.

One idea I had was using the Pythagorean theorem to measure the height or a distance of something outside (For example if you know the height of a ladder and the length of a broom you could find out the height of your garage!)

Any further suggestions on topics I should explore for this lesson? The lesson timeframe is 5-7 class periods.