Marble run features rubberwood blocks scaled to standard Unit Blocks and 4 starter acrylic marbles Children will practice building, explore physics, and learn architectural relationships Set can be rearranged in multiple marble run designs Expand possibilities for constructive play using standard Unit Blocks (sold separately) Set includes 36 blocks (2.75" wide, scaled to coordinate with standard unit blocks), 4 acrylic marbles and 10 double-sided inspiration cards. Ages 3+ Children 3 and up can begin early exploration of physics, STEM lessons and architectural design using the Unit Block Marble Run - 40 pc. set. Rubberwood blocks feature drops, bumps and routed paths that allow for multiple building opportunities. 10 double-sided concept cards provide building inspiration for different block arrangements as well as corresponding lessons related to physics theories. Set includes 4 starter acrylic marbles and 36 block pieces scaled to unit block proportions allowing for multiple run path possibilities.