I like how this application encourages children to work together. Even though the maths is simple, they rely on each other to be successful.
Interestingly what tends to happen is one person from the group takes the lead and directs others. Not something they are told to do, but some just take charge and solve the question quickly and instructs others what to do.
Such a group dynamic makes users passive or active, so it is possible that children don't engage with the maths directly but engage with the person who tells them what to do.
I have seen this application being used by lots of groups of different children and a leader always emerges.