Geometry Lesson Plan Ideas: CPCTC

Context

This is the fifth section of the chapter and the seventh lesson of the unit. Students will need to know the four triangle congruence postulates in order to have any success in this section. Before using CPCTC, they must first know how to prove that two triangles are congruent.

Objectives

Students must be able to prove triangles are congruent by any postulate or theorem necessary.

Students must be able to prove corresponding parts of congruent triangles are congruent.

Resources, Media and Technology

Computer Projector

Computer math program: http://mathforum.org/mathtools/cell/g,10.8.1,ALL,ALL/

Procedures

First I will hand back quizzes and homework from Friday. I will read off the correct answers from the homework and quiz. Then, I will do the two problems from the quiz that most of the class had trouble with. I will ask if anyone wants to see any of the other problems worked out before I move on to the next lesson. I will work out any problems that the students would like to see.To open my lesson, I will do the quick technology activity. I will project a triangle onto the wall for everyone to see. I will see if the students can prove to me why two of the corresponding angles are congruent. I will change the picture on the program and ask the same question.Then I will tell them the statement they will need to make in order to actually prove those angles are congruent.

I will write CPCTC in big, black, bold letters. I will write what they stand for a little bit smaller. I will make sure and emphasize those 5 letters and tell them they must memorize that in order to do these proofs.I will write a sample problem on the board.

First, I will call on someone to tell me if there is any information I can draw into the diagram first.Then, I will call on someone else to tell me if the triangles are congruent. If so, give me the reason why.Finally, I'll ask someone to tell me why corresponding parts are congruent.Then I will do a problem on the board and show them what their proofs in this section need to look like.

I will put a couple of sample problems on the board and have the students work them out. I will once again be going around the room and check for understanding.

I will make sure and ask if everyone had time to finish working out the problems. I will take up their work and give it a small completion grade. With the students help, I will finish up the two sample problems. Then I will assign them the worksheet for homework. I will quickly jot down whose paper I got and hand them back before the end of class.

I will let them know at the end of class that their will be a quiz over this tomorrow.