I wanted to share this tip because it really works for me. It was told me by a friend of mine who has six kids.
When it's all kicking off, the children are screaming, and tension is escalating ...... sit down on the floor and start playing, on your own.
You can play with a toy or do a drawing.
Usually my kids will be distracted from their screaming and come to see what's so fascinating.
That is a great idea - my son isn't there yet but I'll have to remember that... Reading a book to myself is also something I've used when working with tantrumy kids in the past... (was a pediatric speech therapist before becoming a work at home mum)