David is worried about how zany Ruben Plotnick will react when he meets Granma Rosie, whooften says and does unexpected things. Ruben has asked to come to David's house and David is worried that Ruben will make fun of her to their classmates. He wonders what Ruben will do if Grandma Rosie suddenly wants to dance. This is a hearwarming story of senility and school-age embarrassment that reveals the importance of looking beneath the surface to really get to know someone. David is very surpirsed at how Ruben actually reacts to his grandmother. He learns things from Ruben that he would not have known if he had just based his opinion of him on how he behaved at school.