I debated for a long time on the best way to teach triangle congruence proofs. I decided to start with the Math Assessment Project’s lesson Analyzing Congruency Proofs.
I broke it into a multi day lesson since we have 50 minutes classes, and I do not want to rush this! Some students got frustrated with pencil & paper constructions, since they are time consuming. I handed a few students who were struggling a set of AngLegs & a protractor. Boom! they understood what the task was. Next year, I plan to modify this lesson to use the AngLegs instead of pencil & paper to increase student engagement. Once they draw conclusions, then write it down & explain. They even got frustrated and excited and debated about weather or not they could construct 2 different triangles meeting the specified requirements. The most hotly contested one was weather or not they could make 2 unique triangles with 2 sides the same & 1 angle. I thought about videotaping the debate, but I was scared that me pulling out a camera would disrupt the awesomeness. This was all individual work, but tomorrow they will work in small groups and compare their conclusions.