In 1970 Allen Funt made what's considered one of the first experiments in reality film.

This sort of
cinema verite documentary analyzed the crowd reactions of people exposed to sudden shocking moments,like a teacher walking bare naked into a classroom full of mature people. What is interesting about is that also deals with the reactions concerning race relations at the time. For eample,in one moment a black man and a blonde girl walk lika couple into a line at the airport and almost instantly everybody starts giving there dissaproving looks. It's an interesting cinema oddity worth a look.