What you said is demonstrably false.

First, parents provide consent for their kids to be vaccinated.  And it is informed consent.  I know, because I'm a parent and I get the packages of information sent home every years.

Second, this teacher did share the risks (which are not secret BTW), but he also a) failed to provide ANY context about the risk of non-vaccination vastly exceeding the risk of vaccination, and b) he may have done much more in that it has been reported that he was actively trying to dissuade the kids from proceeding.