  We present the result of a pilot study measuring child engagement with the
Lets Make A Story system, a novel mixed reality, MR, collaborative storytelling
system designed for grandparents and grandchildren. We compare our MR
experience against an equivalent paper story experience. The goal of our pilot
was to test the system with actual child users and assess the goodness of using
metrics of time, user generated story content and facial expression analysis as
metrics of child engagement. We find that multiple confounding variables make
these metrics problematic including attribution of engagement time, spontaneous
non-story related conversation and having the childs full forward face
continuously in view during the story. We present our platform and experiences
and our finding that the strongest metric was user comments in the
post-experiential interview.
