A rainbow sentences technique can also be useful in writing: "I want four sentences about the life cycle of the frog. And, as a special treat, you can write each sentence in a different colour."
Using felts or jelly pens in the English lesson is much more fun than remembering four full stops, so the chances children will produce four chunks of text are much greater (you can then discuss whether these chunks are actually sentences). Colour can also help with spelling - to highlight the "tricky bit" in a word.
Children can collect personal bete noir spelling words, with difficult area embellished. Once you've started thinking colourfully, there are endless applications.
The important thing is not to overdo it. As an everyday event rather than an occasional treat, it ceases to be as effective. Time to have another bright idea
Sue Palmer is a literacy consultant