Water%20Marbles%202%20Color%20Liquid%20Motion%20Timer%20is%20a%20great%20visualization%20aid%20to%20show%20how%20water%20and%20oil%20don’t%20mix.%20It’s%20full%20of%20zigzagging.%20Liquid%20motion%20fun.%20Turn%20this%20desk%20toy%20over%20and%20watch%20the%202%20colored%20liquid%20drops%20make%20their%20way%20down%20the%20zig%20zag%20steps%20all%20the%20way%20to%20the%20bottom.%20Assorted%20Colors.%20.