Charlie smiled when Professor Kennedy thanked her for her answer. She wanted to respond with a proud, boastful "You're welcome!" but decided it wasn't a great idea (she had to cover her mouth, though).

She rose her hand a lot quicker for this question. "Sun dials." That's a good answer, right? "When the sun is out, it can tell people what time it is based on its position. The shadows of the sun are like the hands of the clock for a sundial, and they'll align with certain hour lines. You can make a sundial in the sand or dirt or... out of anything you want."

She didn't suppose it would really help at night, though....