A 'Becker Bottle' is named for its designer, Missouri chemistry teacher Bob Becker. The bottle is used as a concrete example for parts concentration.

A Becker bottle is a large (~3L) transparent bottle filled with colored beads. The solvent beads are differentiated from the solute beads based on color. The solute beads are found in proportions that represent concentrations in parts per million (ppm). Typically, the bottle contains 999,999 solvent beads and 1 solute bead. Students are challenged to find the 'one part per million'! Teachers can easily make the bottles, but they are also available from commercial sources.

A straightforward experiment to demonstrate several phenomena is the Cartesian Diver [local]. Plastic pipettes are among the best devices to use for the 'diver.' Robert Becker has devoted an enormous amount of energy to developing useful activities surrounding Cartesian Divers. Some of Becker's Experiiments are available at a related site.