CREATE TABLE teachers (lastname TEXT, firstname TEXT, classroom DECIMAL)
CREATE TABLE list (lastname TEXT, firstname TEXT, grade DECIMAL, classroom DECIMAL)

What are the first names of the teachers who teach grade 1?
SELECT DISTINCT T2.firstname FROM list AS T1 JOIN teachers AS T2 ON T1.classroom = T2.classroom WHERE grade = 1
SELECT DISTINCT "T2"."firstname" FROM "list" AS "T1" JOIN "teachers" AS "T2" ON "T1"."classroom" = "T2"."classroom" WHERE "grade" = 1