After reading about a circulating water cooling cap that was used in a University of Pittsburgh School of Medicine sleep study, the girls set about creating a cheaper, lighter, and less onerous solution the cooling headband.

WHITEHOUSE: The White House

For its principles, the fund drew on tort law, private and government insurance, and welfare, says George Priest, a professor at Yale Law School, but with no consistency and no cap on the amount paid other than Mr Feinberg's sense that Congress did not want a runaway programme.

ECONOMIST: A hard task is over: hard questions remain

She didn't like the grammar school overtones of the earlier sign, which featured a boy wearing a cap and carrying a satchel.

BBC: The road sign as design classic