-- Database schema
| list : LastName [ TEXT ] primary_key , FirstName [ TEXT ] , Grade [ INT ] , Classroom [ INT ] | teachers : LastName [ TEXT ] primary_key , FirstName [ TEXT ] , Classroom [ INT ] |
-- -- Find the last names of the students in third grade that are not taught by COVIN JEROME.

SELECT DISTINCT T1.lastname FROM list AS T1 JOIN teachers AS T2 ON T1.classroom  =  T2.classroom WHERE T1.grade  =  3 AND T2.firstname != "COVIN" AND T2.lastname != "JEROME";