Water bugs manage to stand on the surface of a pond, because the pads of their feet resist contact with the water just like wax paper does. This allows the bug to rest on the thin film of surface tension that naturally covers the pond. This surface tension film is caused by the strong attraction the surface water molecules have toward each other, as well as toward the water beneath them. Learn more on this Moment of Science.
Your five-year-old knows when it comes to building sand castles at the beach, wet sand is much better than dry. If you fill your bucket with dry sand and turn it over, you’re likely to end up with a tumbled ruin, not a proud tower or turret. Any junior civil engineer will tell you to use damp sand from the water’s edge to construct proper parapets. Learn more on this Moment of Science.