Dig

dig the water a way down to the jar.

a cutaway of garden soil: drag a finger to dig tunnels, and water from a pipe runs down whatever you cut, pooling in every dip, until enough reaches a buried glass jar

Water always moves to the lowest open place it can reach, so it takes the shape of whatever you cut: it runs down a slope, fills a dip to the brim before it spills on, and in a U it climbs the far side back toward the height it started from. Stone and glass cannot be dug.

Concepts: gravity, fluid-flow, fluids.

An interactive you play with one thumb, on Wundr.