Find the texts of assessment notes for teachers with last name "Schuster".
SELECT T1.text_of_notes FROM Assessment_Notes AS T1 JOIN Teachers AS T2 ON T1.teacher_id  =  T2.teacher_id WHERE T2.last_name  =  "Schuster"
texts of assessment notes refers to text_of_notes; teachers with last name 'Schuster' refers to WHERE T2.last_name = 'Schuster'; joining tables refers to JOIN operation; matching records in joined tables refers to ON T1.teacher_id = T2.teacher_id;