# Research & Present: Builtin Ruby Methods
__Instructions:__ Divide into teams of four people. Choose one of the _methods_ in the list below to research. Spend twenty minutes reading the [documentation](http://ruby-doc.org/core/) for the _method_ and experimenting with it in `irb`.

After the research period, each group will present what it has learned to the rest of the class. This should include an explanation of the _method_'s utility and an example of using the _method_ in `irb`.

## Methods
- `String.include?`
- `String.swapcase`
- `Array.rotate`
- `Array.first`
- `Hash.invert`
- `Hash.replace`
