Geometry Lesson Help: Congruent Triangles and Corresponding Parts

This is the second lesson of the unit. Students will need to recall how many degrees the interior angles of a triangle add up to. Students will again need to remember how to setup algebraic equations. It will also help students to recall the reflexive property they have learned previously in Algebra I and Geometry.

Objectives
Students should be able to identify congruent triangles and their corresponding parts.

Resources, Media and Technology

None

Procedures
I will return the student's homework at the beginning of class. I will write the problems on the board that the class as a whole seemed to have the biggest problem with. Just before I start the lesson, I will tell the students that what was covered on the worksheet and what we cover today will be on a quiz they will be taking tomorrow. Then I will proceed with the lesson. The first thing I will define on the board is exactly what congruent triangles are. I will draw and label two triangles to demonstrate what congruent triangles will look like when their sides and angles are marked congruent. I will then define to them what a congruence statement is by actually writing the congruence statement for the example on the board. Next, I will draw two columns on the board. One that is labeled corresponding sides and the other labeled corresponding angles. I will call on six different students to give me these corresponding parts.I will then explain that all you need to list corresponding parts is the congruence statement.

Given them this information, I will do another example on the board. This time I will try and call on the quieter students to give me the corresponding parts. I will then draw a football field on the board. I will cut it by a diagonal such that two congruent triangles are formed. I will have students raise their hands if they know how to prove the triangles are congruent. In this example, the reflexive property is demonstrated so I will define the reflexive, symmetric and transitive properties of congruent triangles. Finally, I will talk about the third angles theorem with them. I will write an example on the board and hopefully this theorem will be fairly obvious to them. I will then write 3 examples on the board for everyone in class to attempt. I will go around the room and help any students who seem to be struggling with the problems. When it seems that most of the class has done the problems, I will go back over them at the board. I will have students help me work through the problems. The remainder of class, the students will work on their book assignment.