I'm a little unsure, would you say this is odd behavior from my ex?

That IS weird. You need to have a talk with her teacher and if you are separated, you need to bring this up with the lawyer. I don't know if you have full custody but this is nutso. It seems most men don't mature much beyond age 13 these days - so goofy, nonsensical behavior is to be expected. You might speak with the social worker at the school. There needs to be some boundaries. While it's not unusual for a parent to volunteer to help out at a school function or occasionally meet their child for lunch, this is going to distract her from her social development. At age 10, she needs to spread her wings a bit more than this don't you think? I mean is she having problems with getting bullied and he thinks he is helping the situation? I don't know what the deal is - but you need to get to the bottom of it. Oh my goodness, is he having an affair with the teacher??? I just can't imagine that a teacher or even the principal and other staff would approve of this.