To hearing. Sign is not taught properly in deaf schools either. While we make no claim to be any sort of BSL expert, from what we have seen in deaf clubs the last 26 years some have very poor skills in sign, most appear to lack any sign knowledge regarding detail, it is generalities, 'concepts', and assumptions, some good some not so.
I don't support BSL in schools, it should be Signed English, or Sign supported English so they are better equipped to survive when they leave the deaf set ups and support, and have to work with hearing people on their terms too. Older deaf over 30 already struggle with the 'new' BSL. Being ill-equipped literally, the deaf rapidly on leaving school, begin to struggle and became lost to the mainstream, as they revert to all deaf areas again, where struggles are less, and don't pursue their sign education to improve either, then it all goes to reliance on terps or each other.
Lots of areas have a culture and different language, but the deaf appear pretty singular of the view they need not adapt at all, and that others have to, maybe the reason so many struggle, because you cannot force others to comply, it has to be a willing action. Topically many migrants come here with little English at all, they adapt to survive, deaf can learn their lessons. HoH had to, deafened people who lost all hearing after or during formative education have to, there was no sign, no support, no 'hoh' schools, no community, and no social workers or terps to help them out. The old deaf schools were based on the belief deaf had mental impairments, so education was based on that.
More realism has to be used in describing the 'cure-all' of sign use, but too much is being disguised and lost, under cultural demands and rights, and practicality is being ignored. Trained staff aren't there to equip the demands the Deaf are making, and without those, it is not going to happen. If you accept current 'Deaf' stats then, their current needs required a 100 times more support for sign they they have currently, and take up of Interpreter courses are falling, not growing, as regards to teaching hearing in a mainstream setting, it is very much pie-in-the-sky as the institutional staff do not exist, and the qualification to TEACH needs more than a degree in BSL.. Most born-deaf would fail the English exam qualifications needed to manage HEARING students..
Most deaf seem in a relentless 'blame culture' where hearing are public enemy number one, this is all down to the fact sign isn't effective enough a bridge and needs a third party, or the other person needs to be a signer too, statistically impossible.. HoH and deafened appear to have found a sign alternative. At least they aren't complaining about access. Or maybe they understand the realities.