These marbles are ready to tumble down a run designed by you! Kids discover marble mayhem inspired by our toy of the year award-winning tumble trax when they craft their own marble runs with stem explorers marble runners from learning resources. Using the set’s cling-back pieces, kids 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 kindergarten 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 homeschool or kindergarten classroom use!