Didi and Max are the most competitive best friends in the fourth grade. But their friendship hangs in the balance when Principal Jack announces a school-wide contest to see who can sell the most fertilizer. Didi and Max are the most competitive best friends in the fourth grade. But their friendship hangs in the balance when Principal Jack announces a school-wide contest to see who can sell the most fertilizer. Didi and Max are the most competitive best friends in the fourth grade. But their friendship hangs in the balance when Principal Jack announces a school-wide contest to see who can sell the most fertilizer. Didi and Max are the most competitive best friends in the fourth grade. But their friendship hangs in the balance when Principal Jack announces a school-wide contest to see who can sell the most fertilizer.