Learning Resources STEM Explorers Marble Runners. Great for fun STEM learning in the classroom or at home, children can make their own marble runs on walls and windows. The cling-back track pieces means no permanent adhesive is needed as children build tracks to solve the STEM challenges. The set includes 13 track pieces, 2 balls, and double-sided challenge cards. Includes multilingual packaging and Activity Guide. 18 Piece Set.