SELECT DISTINCT T2.firstname FROM list AS T1 JOIN teachers AS T2 ON T1.classroom  =  T2.classroom WHERE grade  =  1
What are the first names of the teachers who teach grade 1?
[Schema (values) (types)]: | student_1 |  list : lastname (text) , firstname (text) , grade (text) , classroom (number) | teachers : lastname (text) , firstname (text) , classroom (text);