Don't you love that warm, fuzzy feeling? The jar says: Do something kind and get a warm fuzzy. Put it in the jar. When the jar is full you get a class party! Can easily modify for home behaviors - positive reinforcement.
What a great positive group activity! Have one person sit on a chair in front of a white board while the others wrote a positive phrase about them. Take a picture to give to each person. A very creative and positive group activity.