"Science.gov searches over 42 databases and over 2000 selected websites from 14 federal agencies, offering 200 million pages of authoritative U.S. government science information including research and development results."
Previously named FirstGov.gov, this portal opens to a staggering array of information about the United States. Pull down "Explore Topics" and/or "Audiences" to "Teens" for a plethora of choices.