un- and re-

On page 81 of your book, Santoor, there is a little story: Sameer was unhappy because he was unable to find his drawing book, so he decided to redo his work.

Look at the words unhappy, unable and redo. Each one is a short word with a few letters added at the front. Letters added at the beginning of a word are called a prefix. A prefix changes the meaning of the word.

The prefix un- means 'not'. Unhappy means not happy. Unable means not able. Uncommon means not common, something that is not easily found. Unaware means not aware, not knowing about something. Uncomfortable means not comfortable.

The prefix re- means 'again'. Redo means do again. Redraw means draw again. Rewrite means write again. Rearrange means arrange again, put things in a new order. Rethink means think again about something.

So, to choose the prefix, ask: do I mean 'not' or 'again'? For 'not', use un-. For 'again', use re-.