These marbles are ready to tumble down a run designed by you! Children discover marble mayhem when they create their own marble runs with STEM Explorers Marble Runners from Learning Resources. Using the set’s cling-back pieces, children build tracks on walls and windows to solve the included STEM challenges! As they build, test, and tweak their marble runs, kids will also strengthen essential STEM skills, including critical thinking, problem solving, and engineering. All that building is made easy by the cling-back pieces, which require no permanent adhesive and can be used again and again! After they master the set's progressive STEM challenges, kids can even build their own! STEM Explorers Marble Runners includes 13 track pieces, 2 balls, and 10 double-sided STEM challenge cards. This fun learning tool is ready for classroom or home use. STEM Explorers Marble Runners includes 13 track pieces, 2 balls, and 10 double-sided STEM challenge cards. Safety Warning Small parts warning, not suitable for under 36 months