Except for very breif lectures(Key points and instructions)My current class is predominately lab activity. My students and I do mutual participation demos the first six days of the class. Students normally work in pairs during this period,if the pairings work well, I leave them alone, if not I will change a pairing. Most pairs work well with no modification needed, the students are made to understand that after the first six days,All graded tasks must be accomplished absolutely solo! This tack prevents "coat-tailing" as students know from the outset that they must understand,and,more importantly be able to perform graded tasks by themselves.This technique encourages active questioning as well.