I've struggled with this one for years, having seen this experiment in many psych courses. It took me an extra week to get through this video again, just because seeing the responses of the children pained me. I admired how the teacher explained very clearly what was going on, but my issue is the length of the experiment. I believe at that age, it is very possible to leave an impression on the students regardless of intent of the lesson and how much reassurance/guidance is given afterwards to solidify the point. Two days is a long time to have these experiences over, especially since the impact was seen in 15 minutes!
I'm curious to know what others think, since the value here is definitely seen, but it is so rough to watch! It is clear that effects were widespread and not just isolated to the mentality shift, but also treatment of others, self-critical thinking, and possible long-term effects of feeling inferior or even being hard on oneself for buying into being superior. I could see that being very hard to recover from.