A tall tale is a special kind of hero story because the heroes of tall tales are 'larger than life'. An exaggerated, unreliable story: “My uncle claims that he was raised in a drainage ditch, but it's just another of his tall tales.” Examples: Paul Bunyan, Pecos Bill and many others located in the children's section of the library, PZ8.1
Modern Fantasy books are books written about a world that could never be. (Contrast this with Science Fiction which describes worlds that could possibly be, given advances in technology. Some maintain that Science Fiction should be included in Modern Fantasy anyway.)
Fantasy is important for children because it helps them to develop imagination and entertain new ideas or alternative ways of life.
Examples of Modern Fantasy are: