Think about a closet. It contains a lot of things that need to be organised.
1. Think about all the things you can find in a closet and write them down.
2. How can you organise all the things you just wrote down? Put those things in groups and give those groups a name (Pants, etc...).
3. Sometimes you can make smaller groups within a group by looking at the characteristics. Classify the groups based on their characteristics (Blue pants, etc...)