The classic Grimms Ball Run is the spiral–where you set up the rainbow with the end of each arch touching the beginning of the next, and then push the ball gently around the loops to the middle. If you kids are a little older (6ish +?), this updated, self-propelling version of the spiral is a great build for them to approach on their own as, once you have the system down, its really manageable to extrapolate and see what comes next. (video at the end!)
To build this run, you need three sets–the Grimms “small balls” (they come in a 12-pack), a grimms large (12-piece) rainbow, and the Grimms Large Stepped Counting Blocks.
With almost all ball runs, the best practice is to start building at the end, and this one is no exception.
If you don’t have the Large stepped counting blocks, but do have cubes and Color Rally charts, I think you could make it work that way as well. Let me know if you give it a try!
The original Instagram post. When we first built it, the bottom two pieces were on the ground, and the top two were at different heights, but I found it works better as described above, with the top two at the same height instead