active record logical cols

HI,

   I am new to Rails started project couple of weeks back. Here is my
requirement please let me know the solution.

    When I do find on my active record class it returns all the
columns in my database table. I want to add one or two more cols to
the return record.

Like Student.find returns dob and name I want to add age to it some
thing like that. Columns that are not exist in the database table but
I want to add to the return record. How can I do this??

   Please reply asap I am totally struck on this.

Thanks,
Ramu.