SELECT T2.lastname FROM list AS T1 JOIN teachers AS T2 ON T1.classroom  =  T2.classroom WHERE T1.firstname  =  "GELL" AND T1.lastname  =  "TAMI"
What are the last names of the teachers who teach the student called GELL TAMI?
[Schema (values) (types)]: | student_1 |  list : lastname (text) , firstname (text) , grade (text) , classroom (number) | teachers : lastname (text) , firstname (text) , classroom (text);