Just an observation. I know not to rely on the time estimates because I know it will take me a while to write the various programs, etc. in the exercises. However the 2 hour estimate for this chapter seems to be optimistic even for a seasoned ROS developer (the kind of person who wouldn’t need to take this course in the first place). There are 12 exercises - even if you were to be able to work straight through without any errors, I think anyone would be hard pressed to do all 12 in two hours. And given the kinds of people who take these courses, pretty much no way. For future revisions you might want to consider more realistic estimates (even though I know I’ll still be slower than that 
). I think that will help students budget their time better.
/K