You list LGBT students.
That covers Lesbian, Gay, Bisexual and Transgender people.
You do understand that while Lesbian, Gay and Transgender is not a major part of the population, it is a sizeable part. Bisexuals on the other hand are very common. You don't notice them simply because the vast majority are discrete of don't explore their same sex interest.
I expect in that case you would say, as they are not same sex active we would say they are straight.
Okay I will run with that, and say if that is so then a gay (lesbian) person who does not explore their same sex side would also to be considered straight but don't relax as this goes further.
Even more challenging, hows about paedophiles. While some are active, what if you had a past paedophile who says he is no longer active, would you say let him teach at a school????
No you cant do that and so those closet bisexuals will have to join the rest of us. In fact as child abuse is most common a man on girl things, the paedophiles shall be with your lot. Enjoy their company.