I have to take one every three hours, he said.

Japanese children grow up with warnings not to waste a single grain of rice, out of respect for farmers’ labor.

A little red hen once found a grain of wheat.

If you want to train a laboratory rat to pull a crank to get a food pellet, the reflex will be scratched in deeper if the creature is rewarded with some regularity but not all the time.

A current can 'tunnel' across these gaps — another special property of the quantum world, where waves and particles can cross barriers without breaching them.