<p>how do i define a named_scope to return all the records that were created within the last 7 days, and then how do i use that named scope in a controller?</p>

You need to pass named_scope a proc so it will be evaluated every time the call to named_scope is run.  Otherwise if you specify Time.now it will run once (on first call) and be "cached" until the app is restarted.
```
```
named_scope \
    :this_week,
    :conditions =>  [
      %created_at > :time!,
      proc {{:time => Time.now}}
    ]
```
```
You can call the named_scope like
@ar_object.this_week