I am currently reading one paper which randomly assigned students of four classes for experimental and control conditions. However this randomization process was within class and not in a whole, meaning that they had one experimental and one control group in each class, and the intervention proceeded at class- level. The results though were present as a whole (experimental vs control). My doubt is: can this study be considered a randomized control study? Or the fact they randomized within each class is a problem for that?
Thank you in advance and Happy 2021!