Humans, as social beings, are capable of employing various behavioral cues, such as gaze, speech, manual action, and body posture, in everyday communication. However, to extract fine-grained interaction patterns in social contexts has been presented with methodological challenges. Cross-Recurrence Plot Quantification Analysis (CRQA) is an analysis method invented in theoretical physics and recently applied to cognitive science to study interpersonal coordination. In this paper, we extend this approach to analyzing joint activities in child-parent interaction. We define a new representation as Cross Recurrence Block based on CRQA. With this representation, we are able to capture interpersonal dynamics from more than two behavioral streams in one Cross Recurrence Plot and derive a suite of measures to quantify detailed characteristics of coordination. Using a dataset collected from child-parent interaction, we show that these quantitative measures of joint activities reveal developmental changes in coordinative behavioral patterns between children and parents.