Aprofessor wants to examine the effectiveness of a new teaching approach. she has a theory about how this new approach will work, and will use a methodical approach to test her theory. her 9: 00 a. m. class will be exposed to the new method of viewing teaching tapes while her 10: 00 a. m. class will be exposed to traditional lectures. she will assess the students' progress after six sessions. what method is the professor using to conduct her experiment?