This paper introduces a new annotation scheme, designed specifically to study children’s social interactions during play in digital playgrounds. The scheme is motivated by analyzing relevant literature, combined with observations from recordings of play sessions. The scheme allows us to analyze how key social interactions are related to different stages of play and the physical activity levels associated to them. We can use this information for two goals. First, we can identify relations between social interactions and the impact that changing game dynamics have on their occurrence. Second, it facilitates the analysis of automatic recognition of these social behaviors. Results obtained are useful for both goals. They show that it is possible to identify social interactions and their relation to game dynamics. Finally they also allow for further analysis into the possibility of their automatic recognition.