Hi all, wow, thanks for the fast responses and ongoing discussion!
I am definitely sympathetic to the fact that having a teen’s parent in the room may affect the classroom experience - perhaps dampening discussion as mentioned by above posters. Or similarly, having another teen’s parent in the room.
To me, the principle that parents should have access to the catechetical instruction if they so wish is important and should be a fundamental principle. After that is established, then the parents in conjunction with the teachers or the program directors could discuss how or whether this right should be exercised - perhaps breaking out into an adult discussion group during discussion periods, perhaps choosing to assist with another class (instead of the class their own children are in), etc.
Without going into details, I will share that there have been two cases in my own experience (one in a previous parish, one in my current parish) where I was concerned about the catechetical instruction that was being taught, or (in one case) the moral choices (and thus, the living example) that were being made by the religious education teacher. Given all the variety in the church today, some orthodox, some not-so-orthodox, I think it is very important that parents have the option to participate in or attend the religious education programs for their children. Whether the parents actually choose to attend (or not) is another matter.
I agree with the comments above - in most cases, parents will choose not to attend. But it’s an important precept to me that the parents should have the right to attend if they so choose.
Blessings to you all!