When this child sees a sheep for the first time, she will assimilate it into her existing scheme of a four legged animal. Since she has a four legged animal at home and calls it a "cat", she also calls the sheep a "cat".
After her mother tells her the four legged animal is a sheep, this child will accommodate that new information into a new scheme and refer to the animal as "sheep" instead of "cat".
This child now uses the internal process of organization to link together a hierarchy of these schemes. Her scheme of "four legged animal" now has sub-categories of the "sheep" and "cat" schemes. The organization process will continue to rearrange and link together schemes as learning occurs.