Participation Activities (PAs): Some instructors wonder whether students will just click through the Participation Activities just to get points ("cheat the system"), since students can show themselves answers. Our data shows some do, but most do the activities earnestly (see SIGCSE 2017 ASEE 2016), realizing the activities are a good use of time. To achieve such earnestness, instructors should avoid assigning too many sections.
Challenge Activities (CAs, aka "homework"): Some instructors wonder if solutions are on the web like for other textbooks. Some CAs auto-generate problems (if answered wrong, a solution is shown, and another problem generated) so the issue is moot. For other CAs, some solutions may be posted but are hard to find due to zyBook configurability (so CA 7.1.1 is different for different zyBooks). Plus, we do something fun: We can detect if a student submits a solution from the web (we won't say how; don't want to give away our secrets!). Currently only a tiny fraction of students do so, but we monitor the situation to determine whether/how to act in the future.