This site has information about how children grow and develop - and information about education and learning, too.
This site has some free games for building skills in reading and math. (If you join Starfall, you have access to more games.)
While all classrooms and schools are a little different, this guide can give you some tips and helps for your first grade adventure this year.
While a lot of information on this site is geared for younger children, you can find some great resources here for first graders, too.