Now posted in the Formative Assessment and Strategies in Secondary Mathematics page
Tic-Tac-Toes
Tic-Tac-Toes (Think-Tac Toes or Choice Boards) have been commonly used for Differentiated Instruction.  They can also be used to indicate the level that a student is at with a specific concept. Click here for an example of using Tic-Tac-Toes in Math 20-2 and Rationalizing Denominators.