Form differentiated groups in a jiffy! Give students a post it note and have them solve/answer a problem/question on the board. As they hand you their sticky notes, place them on the target in the appropriate section. (Folding them up to maintain anonymity of course!) When you are finished, collect the notes from each section and form groups accordingly.
This can also be done as a preassessment and then again as after teaching the skill. Students will strive to hit a “bullseye” the second time. It’s fun and rewarding for you and your students to compare the “before” and “after” target practice results!
Sometimes sticky notes have a hard time sticking to boards. You might want to place a piece of poster board or a piece of butcher block paper on the board for this activity. You can always save this and then after teaching a skill/unit, you can have "Target Practice" again and compare the before and after results.