We can all think of times when we did not follow the lesson plan or, indeed, did not have one in the first place. So we taught around an intriguing question a pupil may have asked, or responded to something they were discussing.
This is how one of my best assemblies came about. The head of year had a problem with the projector so she asked if I had any good, moral stories I could share with Year 8.
It was the beginning of the year, so I thought about something to reflect new starts and moving on. Before I knew it, I was telling the Buddhist story of Angulimala.
One day the Buddha went out from the monastery and walked towards a great forest. People working in their fields called out to warn him that in the forest lived the dreaded Angulimala, who had been set the task of collecting 1,000 little fingers from the right hand of humans. And because people did not want to give up their little fingers, he was forced to kill them.
Angulimala had nowhere to store these fingers and tried hanging them on a tree but the birds stole them. His solution was to string them around his neck. This is how he got his name. Angulimala means "finger necklace". When Angulimala spotted the Buddha coming towards him he had 999 fingers.
He dashed out to murder the Buddha and complete his score. He expected to easily overtake him and quickly finish the job, but even though the Buddha was only walking, Angulimala couldn't catch him. Eventually, Angulimala screamed at the Buddha to stop.
The Buddha turned and, quietly and directly, told Angulimala that he, the Buddha, had already stopped. He had stopped killing and harming and now it was time for Angulimala to also stop killing. Angulimala was so struck by these words that he threw away his weapons and followed the Buddha back to the monastery where he became a monk and lived a good and peaceful life.
It's amazing how such a graphic image can grab the attention of 250 pupils. I was able to relay the moral of the story - that people can and do change and that they are best influenced by being shown a good example. No matter how bad people have been in the past, they can change when given a chance.
It's also a nice way to remind staff that anyone can change and the pupils that they are not defined by their mistakes. Simply learn from them and move on.
Chris Wheeler teaches at Ashton-on-Mersey School in Sale.