A stop sign causes traffic to stop. We can cross the street safely because of stop signs.
Photo Credit: FatCamera/iStock/Getty Images
In the Know
How Voting Works
What does it mean to vote? Who can vote? People … read more
In the Know
Water Changes!
What do you think the temperature is in this place? … read more
In the Know
What Can Mummies Teach Us?
Some mummies are very old. Scientists can learn from mummies. … read more