A root word is a word on it's own. A prefix is a letter or group of letters added to the beginning of a root word.
Here are some common prefixes:
Knowing what a prefix means can help us to understand new words.
un (prefix) + happy (root word) = unhappy
un (prefix) + well (root word) = unwell
un (prefix) + kind (root word) = unkind
Did you notice how there are no finger spaces between the prefix and the root word? They are all the same word.
Let's have a go at adding the prefix un to some words.