Obtain a ditto of a map outline for an area you are studying. If studying the US, the worksheet should have the boundaries of each state outlined but no state names, capitals, etc. Have the students fill in as much of the map as they can by themselves. Then have them combine the knowledge of their whole table. Later on when beginning the unit or map study, take into account what the class knew altogether, and record this on a larger map or transparency. As homework, they can fill in what they didn't know.