There are many different types of signs that indicate children in the area, but the signs most commonly have an image of a child running on them. They may appear slightly different from state to state and town to town.
Often these signs will be yellow and black, indicating caution. They may or many not have writing on them that states there are children in the area or indicate that the driver should slow down and be on the lookout for children. They are often in the shape of a rectangle because this shape is usually used for signs offering guidance to drivers.