Consider a 9 × 9 chessboard, and you wish to cover as much of it as possible using figures shaped like the one to the right, where each of the four squares is the same size as the squares on a chessboard. The pieces can be rotated or flipped over. What is the maximum number of non-overlapping pieces that you can fit? Here are nine problems exploring coloring, or covering, grids and other shapes.
This collection of problems can be used in a single problem solving session, or as individual teaser questions.