Juan,
If I have had the students in a recent class preceding the new one, I have a pretty good idea where students are, in general. If it's been a while, or they're new to me, a review of past information to build a foundation for upcoming topics in my class is helpful. I try to do this in a fun, non-threatening way. What I avoid is statements like "c'mon folks, this is basic information you had back in [insert class]", or "you should know this". Rather, as soon as I sense a majority of students are struggling with information,… >>>