Oh dear I have rather a lot of things that annoy!
Take time to get to know them 1 on 1 because they won't seek you out / show you what they know - you are going to have to find out. If you do you may find it the most rewarding child you have ever taught - these kids have a way of reeling you in. When you wait months or years for them to say or do something the feeling when they do it is amazing.
Get the 1:1 to do your job for 10 mins and take time out to sit down with them or their small group. You are their teacher as much as any other child.
Dont pretend you have done things with the child you haven't - it is very obvious to us at parents evening if you have had minimal involvement and left it all to the 1:1
Do know whats on their IEP not just file it somewhere and forget about it
Dont assume they can't learn - if they haven't learnt its probably because you haven't taught it in the way they can access it. We decided early on never to assume DS couldn't do something until we had tried everything and proved to ourselves he couldn't do it - there is nothing we have tried to teach he hasn't learnt - some of it took months or years but he has got there in the end.
Sometimes its not an inability to do it, its just they haven't understood the expectation - try writing it down as a set of rules - lists and ticking things off helps it may not have to be pictures.
They can be literal so say what you mean and mean what you say
Teaching them the routine of your class can take weeks so don't change it on a whim just as they have got it - if you want to change it prepare them in advance
Priming really helps - if you are going to do Goldilocks tomorrow get the 1:1 to do some work on it today then they are more likely to be able to join in. Sharing planning sheets with parents and 1:1 helps as can gather resources / prime at home / reinforce.
Repetition is crucial. Give them lots of opportunities to practice the skill. If they don't get it don't be afraid to pull them back and do it again - several times in a row if necessary. They will learn better with repetition than coming back to it once a week
Figure out at the start what their attention span is then start working up from there not from where the other children are. It might be 30 seconds and you work up to 1 min. Making them sit for 10 mins when their attention span is 1 is setting them up to fail. Always aim for just one step ahead of where they are at so they have lots of experience of being successful and rewarded for that and are more likely to progress.
Use rewards that are motivating for them. My DS has a token board and earns points (this is how we have expanded his attention span from 30 seconds to 30 mins). When he's earned his points he gets a choice of activity e.g. book corner, running round playground with 1:1, a go on computer. He isn't motivated by marbles in jars for the end of term or not being told off, or other children's disapproval. He will work for things that matter to him. He still has more breaks and different rewards than the rest of the class - the other kids accept it its not a big deal - we wouldn't have gone from 30 seconds to 30 mins if we hadn't individualised rewards and breaks
Playtime is work for them usually the hardest bit of the day. Its a confusing exhausting noisy mess. They may need downtime when they come in from playtime e.g. 5 mins in book corner.
Sticking with one thing until they have got it (in a linear / hierarchal way) often works better than the dipping in and out, coming back to it a few weeks later approach that seems to be the trend for other children. Working systematically through a list of skills and ticking them off one by one is more effective. Whats more you can share it with parents and reassure them they are making progress.
They really don't always need to know 3 different methods of multiplication - I would be happy with 1. Think about whats functional. Where do they need to get to by 18, what skills will they need, work back from that. Don't waste hours on the grid method … when in real life they will use a calculator - when you could be doing extra time on language etc
Don't get taken in by the hype of SEN products - numicon is fab but while it worked great for adding the concept of putting a small piece on top of a large piece and counting the holes that were left for subtraction made no sense - as far as he was concerned he was still adding the holes from both pieces together. Using counters and physically taking them away worked much better. If one thing doesn't work try it a different way. The internet is full of egs. Sometimes something gets put on the IEP as a resource to use and thats all that is used even when its not working.
Often outside professionals know very little at all - they have only been on a few 1 day courses too. Sometimes this makes them rude and defensive around parents as they know the parent knows more than them.
You are going to have to test what the child knows in different ways as they may not answer, not tune in, may just repeat back the last thing you said or have memorised the whole book word for word without any understanding. My DS rote learning ability tricks many experienced teachers all the time.
Teach the language of maths. My DS can do it numerically but word problems he can't do at all. Its a language not maths issue. 'circle the right answer' to my DS means circle the one on the right not the correct one! He can trip up on maths problems just because of the way the question is asked. One child at GCSE asked about the humour in a book wrote 'there isn't any' because they didn't find it funny. You are going to have to teach them to answer the question in the way a neurotypical person would expect them to interpret it not the way they necessarily would. In both these egs the child didn't actually get the question wrong given the way it was asked!
Do not assume they can't cope - my DS has never been allowed to speak in a school play even though he's fully capable. Yes he would have been too quiet / needed prompting etc but so were lots of the other children. Ask the parent what you think will work and give them the same chance of trying and failing as any other child. The year the teacher refused to let him speak one child ran out of the hall, one fell off the stage, 2 forgot their lines and several were too quiet to be heard but my ds was the only one not allowed to try. My DS got so bored in one school play when some children played the drums and there was one boy missing he grabbed the drumsticks and joined in in perfect time - but he's never been picked to play an instrument in an assembly / play either. Low expectations and assumptions of failure really really annoys us.
Dont inflict surprises on them - the number of times the lights have been turned off for assembly for father christmas or the visiting magician and the other kids whipped up to a frenzy so they scream their heads off and noone thought about the impact on my DS well I have lost count. Do the surprise for the other kids and let this one join when the screaming / frenzy has stopped.
Do video their successes and share them with parents or write a short note each week. When your child can't tell you about their day school is really just a big black hole (plus it will get us off your back)