From the time I spent observing and teaching in a school for the Deaf, I found that maths lessons were the ones most like lessons in a mainstream school. The main difference is the fact that because class sizes are so much smaller (between 5 and 9 children), lesson objectives are more targeted for each individual child rather than having the same objective for a whole class or whole set.
There is also more support – two to three TAs in each classroom – so during independent activities each group still has an adult to support them. The children are mainly below the level of their peers in mainstream schools, because of their delay in language acquisition. However, teachers still have high expectations and lesson plans have both age-expected learning objectives, to make sure that staff bear in mind where these children *should* be, as well as realistic objectives.
To help the children catch up, they have two maths lessons a day – an hour-long one in the morning in their own class, and a 15 minute ability-grouped one in the afternoon which focuses on particular areas of weakness such as mental calculations and maths vocabulary.
Teaching is, obviously, very visual and kinaesthetic and happens mostly in English with signs to support.
In the lower school, children can choose whether they record their maths in figures or pictures. Some are happy to write 4 + 3 = 7, but many prefer to show this as 
and either is considered acceptable. Higher up the school they record their work in figures only.
One thing I became very aware of during maths lessons, is that for some children, having BSL as their first language hinders their maths. For example, hearing people naturally count on both hands whereas counting in BSL is done on one hand only: you start with your thumb for one and put up an extra finger for each number up to 5; then you come back down again, so 6 is represented by just the little finger, 7 by the little finger and ring finger together and so on. Now imagine trying to do 7 take away 2 on your hands: you put up two fingers to show 7, and then take away 2…… Hardly surprising that 7-2=0 appears so often in their books…
With so many extra obstacles in their way of their learning, it’s a true testament to their perseverance, and their teachers’ dedication that they manage to learn.
Related posts: Literacy in a School for the Deaf Deaf Studies in a School for the Deaf