CK-12 Foundation
Ck 12: Linear Pairs
[Free Registration/Login Required] Students explore the concept of linear pairs by navigating through the interactive learning module and then answering questions that go along with the module.
Texas Instruments
Texas Instruments: Congruent Triangles
This activity works with a PowerPoint presentation to have students answer questions as to what method a pair of triangles can be proven congruent: SSS, SAS, ASA, AAS, HL.