Similarly, the percentage of respondents between the ages 30 to 49 who say parents do not put enough pressure on children has increased by 13 percentage points since 2006.
With standardized test scores in the U.S. dropping in recent years, some administrators believe students need to spend more time in the classroom instead of on the playground.
Recent evidence favors a rival to the long-standing theory that the Americas were colonized 11,000-12,000 years ago by people migrating south from Beringia along a midcontinental ice-free corridor.
But two U. s. researchers, a transportation expert and an atmospheric scientist, decided the time had come to apply blue-sky thinking to one of the world's greatest challenges.