NameError, uninitialized constant States

I'm completely new to Ruby and Rails and could use some help resolving
an issue. I have a list method that is supposed to show the titles and
states(status) of requests, but I get an error from this piece of code:

     <td><%= change.states.state %></td>

The error is:

`const_missing': uninitialized constant States

The states table contains an id and state field. The changes table
holds a foreign key named state_id that references the states table.

I want this code to simply display the text from the state field for
the specified change request.

Can anyone tell me what's wrong?