According to https://en.wikipedia.org/wiki/Institutional_review_board#Exceptions
"Research ... involving the study of instructional strategies or effectiveness of various techniques [and] curricula ... [or] intended to assess the performance or effectiveness of public benefit or service programs" are exempt from IRB oversight.
Source: http://www.hhs.gov/ohrp/humansubjects/guidance/45cfr46.html
Best regards, Jim