Since 1600, telescopes have used lenses or mirrors to gather and focus light.
1. sentence
2. fragment

On november 17, 1968, football fans across the united states sat glued to their televisions. a close game between two top teams—the new york jets and the oakland raiders—was being broadcast. when the jets pulled ahead with only fifty seconds remaining, viewers went wild. but then, just as the raiders were bringing the ball across midfield, the game disappeared from the screen! in its place, a previously scheduled children's movie, heidi, started playing. callers flooded the tv network's phone lines, but it was too late. the raiders scored two touchdowns in the very final moments—touchdowns that were unseen by all but west coast viewers. as a result of the interrupted event, dubbed "the heidi game," television networks began delaying their regularly scheduled programs until football games had ended.