Dr. Root taught mazes to the beginners. After Dr. Root presented a sample maze on the demonstration board, students set up a mazes for each other then captured each chessman in the maze with a rook. From Science, Math, Checkmate: 32 Chess Activities for Inquiry and Problem Solving.
For intermediate and advanced groups, Dr. Root taught the en passant rule. The intermediate group then played a Pawn Game (see Science, Math, Checkmate: 32 Chess Activities for Inquiry and Problem Solving). During the pawn game, players raised their hands if they thought they had an en passant capture. Dr. Root checked to see if indeed they did have such a capture.
For the advanced group, students attempted the "Create" challenge from Thinking with Chess: Teaching Children Ages 5-14. In that challenge, students tried to create and to notate a chess game with three en passant captures in it.