A prefix is a letter or group of letters added to the beginning of a word. Knowing what a prefix means can help us to understand new words.
Some prefixes are easy to recognise. For example, un- changes a word into its opposite.
lucky / unlucky
Prefixes change words in lots of other ways, too, and in this worksheet you can practise using a wide range of them to make new words.
You may find a dictionary helpful if you don't know some of the words.