Lemonade Wars by Jacqueline Davies

Loved it!  Moved a bit slower than any book I've read recently, but is a great story about brother/sister relationships.  Big brother is upset because little sis will be skipping a grade and be in his classroom in the fall.  Covers all of the angst and anger that he is feeling as well as her not getting why he is upset.  Good, clean read about two siblings who really do love and enjoy being together even though a lemonade stand competition would lead you to believe otherwise.  Has two sequels that I have not read yet.