Research into dying minority languages shows how to measure if a language is threatened and how to revive them, and recent research using these measurements with British Sign Language (BSL) found that it is severely endangered (Deaf Ex-Mainstreamers Group - DEX) . Approximately 3 - 4,000 deaf children in the UK are learning BSL, which, if this trend continues, will mean a very small group remains in a few decades as older Deaf people die. BSL will struggle to survive with such a small number of users, as will the BSL using Deaf community.  BSL is the natural language of deaf children regardless of their level of hearing loss, as hearing aids and cochlear implants do not give enough amplification for them to hear in the same way as hearing children do. This means that they have to "always calculate": to have to learn to listen via unnatural means and make their own interpretation of these sounds, and to learn to lipread which requires high levels of concentration and working out what is being said from the 70% of shapes that are not seen on the lips. Having to always calculate on a daily level in schools, and throughout life,  places an enormous strain on deaf children. Most are in mainstream education with no other deaf peers, as well as trying to make sense of the national curriculum and the school environment. There is also the "unwritten curriculum" where children learn from home, peers, and the media which research points to being 11% of children's knowledge achieved outside the classroom. This is greater for deaf children who are unable to overhear and who struggle with English so are often unable to read information without support. There are gaps in academic performance as potential is not fulfilled. It is important that all deaf children learn English to the best of their abilities, to read and write, speak if able, and support with lipreading so that they can be employed and active citizens. At the same time all deaf children need BSL so that they can learn via their natural language, as research shows that it is easier to learn a spoken language if sign is the first language. Deaf children also need BSL to belong to the Deaf community, make relationships and friendships in a natural way, and have a positive Deaf identity. The Deaf community is calling for a BSL Act, which must be a language plan based on DEX's language planning research, and to make sure there is no continuing waste of public funds, so that deaf children will have quality of life.