It is so easy to forget how old the children that we teach are and, in fact, to forget that they are children. In so many schools we are pushed to see them as statistics (do 'he's one of my lowers', 'she's a step 23', 'he's pupil premium' ring any bells?) that it is very easy when we first get our class to forget that we're not teaching numbers but people. Obviously, we know they're people when we're interacting with them, we can see it but even so, sometimes a little bit of us forgets.
When we forget that children are children, we forget that they are going to behave like children. We think that because we told them how to solve that maths problem, to include capital letters and full stops or to stop talking, that they will and can do it. Unfortunately, people make mistakes (and this includes little people) and they don't always understand.
I had a Year 3/4 class quite a few years ago. My previous class had been Year 6. It was mid-October and I was getting really quite frustrated that some of the children in my class were being really quite childish (yes, I realise now that this is because children are the reason the word childish exists but back then I hadn't understood it). Part of me had forgotten that I was teaching 30 people, not two level 4s, 7 level 3s, 14 level 2s, 3 levels 1s, a P8 and a P7. The numbers had overridden the important bit. One day, the mum of one of my very grown up (read: overly confident) Year 4 girls was a few minutes late to pick her up. I watched as the worry quite rapidly started to grow in her eyes and the relief that arrived when she saw her mum walk down the path. But, it was the cry of 'Mummy!' that made me sit down after she had left and go 'Oh no, I'd forgotten that they're only 7 and 8.' Their annoying little habits got a bit easier to deal with after that.
So, next time your class is doing your head in by being children, try to remember that, as much as SLT want to push the data, the bit that matters the most is the children and, sometimes, it helps to remind ourselves just how young they really are.
TLDR: remember, children are childish because they are children. When you are finding it a challenge, remind yourself how young they really are.