Why are traffic lights green, yellow, and red?

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Traffic lights have three colors, and that's all the information that drivers need to get through intersections safely. Green means, "Go." Red means, "Stop." Yellow means, "Stop if it's safe to."

The colors of traffic lights come from signal lights that are used for railroads, which have been around longer than cars. Red was the first choice for "stop," since it's always been associated with things like danger, blood, and fire. It's a very good warning color!

The other colors changed over time. Green is a good choice for "go" since green is the farthest color away from red. If you think about mixing primary colors, green is made from mixing yellows and blues every color but red!

by   (whyzz writer)
  • Exploration

    Red Light, Green Light

    Have you ever played Red Light, Green Light?  One person plays the traffic light and everyone else has to try to tag him or her.  The person who is "it" stands still with their back facing the other players, who are in a line.  When the traffic light says, "Green light," the players can move. 

    At any time, the traffic light can turn around and say, "Red Light!" All the players have to freeze.  Anyone caught moving has to go back to where they started. 
    After everyone freezes, the traffic light turns around and says, "Green light," again.
    Whoever tags the traffic light first wins and gets to be the traffic light in the next round. 

    Try playing with your family and friends!
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