I created these applets to go with guided worksheets to help my students understand what happens to the slope of a line when you rotate it 90 degrees and 180 degrees and why.
This applet uses slope triangles to show the slope triangle rotated 90 degrees. This illustrates how what was the change in x is now the change in y and the sign has flipped and what was the change in y is now the change in x.
The applet below uses slope triangles to show how the slope ends up being the same when the line is rotated 180 degrees.
I made this applet for my students to explore and develop a better understanding of each transformation.
I made this for my students to explore parallel lines and what makes them parallel or not.