Section 7-4 of the U of Chicago text is on overlapping triangles in proofs. When the triangles to be proved congruent overlap, this can be confusing for the students. Indeed, I admit that even I, when I saw Example 2 in the text, was confused as to how to complete the proof!
I have an activity planned out for this section for tomorrow. But my main objective is to make sure that the proofs of SSS, SAS, and ASA are posted. I did say before Thanksgiving that I wanted to have these up by today! If you can see these, then my scanner is working!