You're still conflating the concept of "equality under the law" with the concept of personal/religious opinions about what is "right" or "normal".Yes. I was using the word opinion because that is what you chose to use.
The state has values that are enshrined in law and those values say that homosexuals amongst others deserve full legal equality. Therefore the schools should be reinforcing those values, not pretending gays don't exist.
Let's cut to the heart of the matter. Gay activist groups don't want same sex relationships "taught" in school just to let kids know that such relationships exist (kids know already, from TV if from no other source), and that the law recognizes such relationships, and that persons in such relationships are entitled to equal treatment under the law and freedom from harassment. They also want children to be taught that such relationships are "normal" and "right", and that homosexuality bears no moral or personal stigma. If I was gay, that's certainly what I would want.
Many people do not see homosexuality as "normal". Other people (usually on religious grounds) don't see homosexuality as "right". Both groups are entitled to their opinions, and so are those people of the opposite view. But it's this latter debate that should not be staged in the schools, and it's particularly wrong that only one point of view would be presented, as teachers still do occupy a position of authority with at least some of the children being taught.