Before giving my Algebra students a summative assessment on concepts of ratio, rates, percents, unit conversions, and exponents, I like to give them a group/practice test about a week prior, to give them a chance to study together before the "real" test a week later. (If I call it a "review," they treat it as a homework and just don't take it seriously!) They work in cooperative groups of 3 or 4, and since my students change groups every 3 weeks, I choose who their groups will be.
I weight it