Marbles run through the cube blocks with slanting holes and channels, and run along the tracks by gravity. 60 Pieces Wood Marble Run Blocks Play Set: The set includes a good variety of 50 wooden blocks and tracks, 10 glass marbles and a basic builder manual book Open-ended Play: Marble runs are the ultimate open-ended toy. Kids can easily follow the step-by-step guides that shows them how to build tracks, or challenge to create their own marble mazes, there's endless building possibilities Collaborative Play: Marble runs are also often collaborative.The set is compatible with other Onshine wooden marble runs set that can extend play options, enough for children play together, it helps develop co-operative skills of communication, discussion, negotiation, and compromise.