CK-12 Foundation
Distance Between Two Points: Segment Addition
Examine the segment addition postulate through an online simulation activity. An interactive lesson allows scholars to manipulate points and watch as the lengths of segments change. Through their study, they are able to apply the Segment...
EngageNY
Triangle Congruency Proofs (part 1)
Can they put it all together? Ninth graders apply what they know about proofs and triangle congruence to complete these proofs. These proofs go beyond the basic triangle congruence proofs and use various properties, theorems, and...