I'm 60 in a couple of months.
I remember this was a thing, but I don't remember it at school, but I was at a girls' school and I associate the impressions with boys.
Also it depended which channel you watched, we were not allowed to watch ITV children's programmes so would have seen this.
Kids can be cruel, and the younger they are the more they may not understand just how cruel they are.
Also in the 1980s disabled people were often living in institutions or attending special schools where, according to Laurence Clark he was taught to cut out coloured paper.
I was teaching some teenagers when it was the anniversary of 9/11, which I experienced as an adult. I asked if they remembered it as they would have peen primary age.
One of the students said all the boys were taken to the hall and told not to 'play at 9/11' as it might upset the girls. I think it was impressions of planes hitting buildings and faking jumping from windows. I'm not sure how I feel about the splitting up of boys and girls but I trust the teachers knew them better.
I would imagine any child who took part in the 9/11 games will probably be mortified that they did.