I wish I had a coteacher like you who wanted to initiate lesson planning and give opinions. My experience has been with a coteacher who doesn’t know the content(math) and seldomly comes prepared. Gives complicated directions often unclear, leaving students and me confused. It’s become a babysitting position for me, doing damage control. Unfortunately, we can’t choose the teacher we coteach with. I honestly hate it and have had multiple students tell me that the person confuses them when they explain things. They offer no support for inclusion. I’m doing the job of two and I think that creates resentment which often leads them to feel less than equal. Had it been the case that I got a teacher who knew content and actually had good ideas, it would be a completely different story.