In this section students prove that if triangles are congruent, then all corresponding parts must be congruent, and they start developing the language they will use to prove triangle congruence theorems.

As students progress through their study of proof, they have opportunities to create their own proofs as well as see models of increasingly formal language with which to express...

In this section students apply the triangle congruence theorems to write more proofs. They consider the diagonals of quadrilaterals, angle bisectors, and isosceles triangles. Students have the opportunity to engage in all aspects of the proof process: generating conjectures, detailing specific statements to be proved, writing a proof, and critiquing a proof. They continue creating auxiliary lines and encounter the...

In this final section, students have the opportunity to apply their thinking from throughout the unit. As this is a short section followed by an End-of-Unit Assessment, there are no section goals or checkpoint questions.

In this section students prove the three Triangle Congruence Theorems and apply these theorems to prove other conjectures. Students begin this section with the skills to prove the Side-Angle-Side and Angle-Side-Angle triangle congruence theorems. They then pause to prove the Perpendicular Bisector Theorem in order to use it in the proof of the Side-Side-Side Triangle Congruence Theorem.

There is an...