I watched the video "Using Dynamic Geometry". Here are my notes:
Created hexagon by rotating lines. Created tessellated pattern by rotating. Teacher liked that she could get instant results. She could move faster to the reasoning and the proof. Higher level of thinking and learning rather than just spending the day drawing. Asked students why the pattern fit so well with the hexagons. 120 degree exterior angle. Student said it's easy and quick and you can see how angles fit better than if you were drawing, because drawing isn't perfect. Even with the software students have to know the math to know what they're doing. Looked at rotations of the hexagons. Then looked at pentagons and saw that they didn't work like the hexagon. Students could explore the math of the exterior angles fast because of the technology.
Next teacher had class find shapes in the pattern of circles that he gave them. They had to find the shape, justify it to themselves, to a friend then to the teacher. Let students look at properties of circles (radius, 360 degrees) and the properties of the shapes they're finding. GSP makes it so students don't have to worry about drawing correctly, the program does it for them, but they have to give the program the correct instructions, which requires students to understand the math. Gives students opportunity to prove why they know they see certain shapes. Program allows students to more easily point out properties once they have discovered them. Write it on paper is good, but you loose the interaction of talking about it and explaining it. GSP then allowed students to reproduce the proofs for the class without the effort of drawing.