Read Chapter 4. Deemphasize the non-obtuse-angle theorem (pp. 185-186) and "Note for advanced students" (from p. 188 through the top of p. 190). Also, we will not have time to study the proofs in this chapter as thoroughly as those in Chapter 3; however, the statements of the propositions (especially in the Saccheri-Lambert sections at the end) are very important for understanding later chapters.
In addition, each team should turn in a single written version of its proof.