Actually, no, that is legally not true in the United States. That is why I asked if you read the paperwork you signed when you sent your child to school. That is why I mentioned "in loco parentis." It has gone to court. That latin phrase means "in lieu of parent." You quite literally signed away your rights. You can google it. Your child has no right to privacy, no right to assembly, no right to speach, no right to medical treatment they request. It is completely the school's discernment. Those are exaggerated examples, and I do not wish to derail this thread, but it is catagorically not true that you are reponsible for your child at school. You need to look it up. You relinquished those rights.
Those are examples of the child not having rights. The parent, however, still has rights to/over the child. If I want my child to assemble or protest or get medical treatment, then I can take them out of school at my discretion (barring legal/custody issues).
Obviously, pulling a child out of school to assemble or protest comes with the risk of unexcused absences; very few of our rights don't have consequences. But, that does not mean I don't still have responsibility for my child.
Since parents ultimately have the right to completely remove their child from school to homeschool, I think schools have an obligation to provide parents enough information about their child's progress to make an informed decision.