'Magic sand' has a special coating that prevents water from clinging to it - that is, it makes the sand hydrophobic ('water-hating'). When ordinary sand meets water, the water clings to the sand, getting it wet and making the grains stick together. However, water rolls right off magic sand, so it doesn't get wet.
It's like magic, but it's actually science!
Wet and Dry printable guide.
This activity was developed and tested with preschool and kindergarten educators as part of Science World's Big Science For Little Hands program.