With the heart in the branch
All the children each have their own heart hanging from the branch and every day Santa comes by with a letter from Santa. In the letter, he writes, among other things, some nice words about a child.
Preferably good qualities, nice things it has done, etc. The group guesses who it might be and that person gets to take down their heart and hang it in a new pane in the window. Exciting and lots of focus on social competence.