[GaryVoshol]

Let's change the situation. Suppose a student couldn't come to robotics because she had tutoring sessions. Would you be encouraging her to skip tutoring to go to robotics? Of course not, because tutoring is important; maybe she would fail a class without it.

So it comes down to priorities. What is important to the student, overall? Basketball seems to be important to him (or he wouldn't do it); only he knows the reasons why. You mentioned pleasing people and not letting down the team, but you also said he enjoyed it. So he should be free to do basketball if that's what he wants to do.

You have options. As others mentioned, perhaps you could change some team meeting times. My thought is that you should recruit new team members, or encourage other existing team members to come more often, so that you will get more than 2.7 people at a meeting.

Some robotics teams require strict participation rules. Others will accept members for the time that they can give, as long as they are productive members when they do come. Obviously there must be some limits; someone who shows up 4 times in the six week build season isn't a committed team member.

It can be a challenge. I remember one sub-team leader on my daughter's team who didn't show up for about a week because he had to work, and the part of the robot he was working on fell behind schedule. Those kind of things can be resolved by better communication and having backups for when someone can't be there. But you can make it work.