This paper reports on a large clinical study with 193 children (Grades 3-6) who interacted with 12 digital math games during clinical interviews. Children completed a pretest, interacted with the digital math games, completed a posttest, and answered questions about their interactions with the games. During the interviews, researchers used two video perspectives to capture children's interactions and onscreen gestures. Mixed methods were employed to analyze pretest and posttest data and to examine how the design features in each digital game afforded learning opportunities for children. The results showed that children exhibited different levels of awareness of the design features, some features helped or hindered different children, and children who were able to connect the digital games with the mathematics in the games exhibited higher learning gains.