The experiment was planned to last three days. It was stopped after less than a day and a half. I remember the principal coming on over the PA and announcing that the experiment was ending immediately and that treating any "Others" any differently from then on would result in a suspension. There were students showing up in the office crying about it. Not just complaining. Literally in tears.
The problem, primarily, was that it was a middle school. There's already a group of students that all the other students mistreat or pick on or don't respect as well. There's already a social pecking order. When some of those low social rank students were assigned to the "Others" group, they really got bullied by people. What I remember being the most shocking was how several teachers were bullying and treating students badly. Yelling at them or punishing them for no reason at all. Just because they had a paper sign that said "Other" on their shirt.
The thing that this drilled into me is how vile people can be to each other when they think they deserve it or otherwise aren't deserving of basic respect or equality. The older I get the more I look back on this little experiment and am shocked by what happened. Xenophobia and sectarian divisiveness is a remarkably easy way to dehumanize and strip other people of basic human rights. It's really quite terrifying how easy it was and how quickly it happened. How all the students and staff just readily accepted the new social order because that's what the authority said was true. How people abused that social order for no good reason. How people who were ostensibly pretending were actually acting in horrific ways. It's difficult to know in the moment what's acting and what isn't when it's a stranger doing it.