Evaluating Concept Learning: Research design
In the recitation vs. tutorial experiment at the University of Maryland, only one hour of instruction per week was modified over a period of 5 years in random classes.
Twelve different faculty taught the classes — only one of them the researcher.
Two instructors taught twice— once with recitations and once with tutorials. In both cases the tutorial result was substantially better than the recitation result. (Dh > 0.15)
* E. F. Redish, J. M. Saul, and R. N. Steinberg, Am. J. Phys. 65, 45-54 (1997)