Watch out when you get to Activities 8-1,2 and 3. There is a marked increase in difficultly here. While Rossman continues to present the material clearly there is not enough explanation for students to understand the material solely through discovery.
I just read Moore's explanation of r^2 in setion 2.3 of BPS. His use of the phrase "variation in y-hat as x pulls it along the line" finally gives this visual learner something to hang my understanding on.
I am going to have my students spend one nights assignment on 2.3 of BPS before going on to finish Topic 8.