Students have such a hard time visualizing intersecting planes. It helps so much if they have something concrete to hold.
I have a giant piece of foam board that I cut in half, and then cut slits in. A saw works nicely for this :)
Check out how awesome this looks once the foam board is stuck together.
I use my giant foam board to introduce the lesson and talk through the main points. Once I’m ready to have students start taking notes and dive into specifics, I pass out two notecards to each student. I have them tear notches into the notecards to show intersecting planes.
Then, I have students stick their pencil through the notecard to show a line intersecting the plane.
After that, I have students put the two planes together and use their pencil as a line.
This works so well to have students visualize things. Their homework typically involves true and false questions for this lesson, so I have them get out their notecards if they get stuck!
