DS is four. We haven't decided whether we're sending him to preschool this fall or not. We are above the level that qualifies for free preschool but we will have trouble paying the exorbitant preschool costs ourselves. He is of average intelligence I think, he knows his ABCs, can count to 50 or more, can spell his name and a few simple three or four letter words, is learning to write, and can dress himself and do other "big kid" things. What else would he learn in preschool that I haven't taught him at home? Is preschool necessary?