A catalyst is a thing that makes something else happen. In a story, it's not the story part itself - it's what makes the story part happen. It's the turning point, the thing that sets other things into motion or the spark that lights the flame.

Usually, a catalyst is something that comes in from outside to unbalance a situation. In a story, it might be someone or something new entering the scene, or someone exiting through death or abandonment or some other reason. It can also be that a character sees things that he's always seen, but now through a new lens. Whatever it is, the catalyst requires action. It changes the situation so much that the characters have to do something different - they can't remain the same. They have to make some kind of decision.

I've been teaching the idea of 'catalyst' to the Year 6 writing groups this week. I gave them a set up, including a character, and what the character wanted, and then asked them to write the catalyst which would get the story actually going.

But it's been interesting to think about the idea of catalyst in my own life. Everyone has turning points. Mine have been often at changes of circumstance - I think of going to boarding school at 11, returning to Australia at 16, university at 19, and life changes like marriage, children, birth and death. 

Funnily enough, the catalyst that set the wheels in motion for us to have our fourth baby came from my husband's desire to buy a new car. Long story, so I won't bore you, but the car discussion set a whole other discussion into motion and the culmination was a gorgeous little baby girl.

What have been the catalysts for major changes or storylines in your life?