In a 1786 letter to a friend, Thomas Jefferson called for “the diffusion of knowledge among the people. No other sure foundation can be devised for the preservation of freedom and happiness.”1 Jefferson saw clearly what has become increasingly evident since then: the fortunes of a nation rest on the ability of its citizens to understand and use information about the world around them. We are about to enter a century in which the United States will be even more dependent on science and technology than it has been in the past. Such a future demands a citizenry able to use many of the same skills that scientists use in their work—close observation, careful reasoning,.