The program was administered by professors from York College (part of the City University of New York). As I recall, we had a math professor, a Spanish professor, and a speech professor. The remaining subjects (social studies, English, gym, etc.) were taught by the staff of the junior high school. I should also mention that the school wasn't in my district; in fact, it was a newly built school (IS 238 in Queens) at the time. Due to overcrowding, my local junior high (IS 59) could not accept any fifth graders from my local grade school (PS 132), so either way, I would have wound up there.
Unfortunately, I don't remember a whole lot about what I learned in class (but I might if I try). I know there was one day that we learned about graphing on the real number line, and the formal notation of set membership (ε) was used. There was one day when the speech teacher tried to determine what our accents were from speaking a few words. In some ways, the classes taught by the professors were free form, whereas the ones taught by the regular staff were more representative of what a sixth grader would have learned in a public junior high at that time.
One might think this was a preferable alternative to the traditional sixth grade experience. Well, maybe not. My parents pulled me out of the program at the end of the school year and I went to my local junior high for the next two years. My parents were unhappy with the program for several (justified) reasons. Among them was that the professors didn't always show up. Oftentimes, no sub showed up either, so you had unsupervised sixth graders roaming around the school ... not such a good thing, in my parents opinion. There were some other issues, such as occasionally unreliable busing from the junior high to my neighborhood.
I have sort of mixed feelings about getting pulled from the program. I had friends that I didn't want to leave. I also liked the classes. There were a number of things about my local junior high that I did not like (too many to go into now). But in all fairness, the teachers showed up when they were supposed to, and a qualified sub was provided when they were absent. Also, I had an excellent Spanish teacher. My sister and I are both in agreement that he prepared us very well for high school Spanish. I can still remember a lot of the things he taught me. And all things aside, I was still able to pass the entrance exam to get into Stuyvesant, where I was reunited with some of my friends from sixth grade. (More on that later as well.)
On a somewhat related topic, I stopped off at the Mtn View library on the way home yesterday evening to do some copying and a bit of browsing. I happened upon a math book called A New Look at Arithmetic by Irving Adler, copyright 1964. I was curious to see what it was about and discovered that I had actually read that book when I was in grade school. According to the intro, the book was designed for teachers of the so-called "new math" of the time, and parents who had kids that were learning said math. I vaguely remember that my mother (who was a grade school teacher) took a lot of work-related classes, so possibly she used this book. (It could also explain how Isaac Asimov's Realm of Numbers came into my possession.) One of the things I really liked about the book was their description of different numeral systems, e.g. those that were used in the Middle East several thousand years ago. Some were more like hieroglyphics than today's numerals. Someday, when I have more time, I will do some reading on the mathematical discoveries of the Babylonians and other peoples of the Middle East and Africa. I recall being very interested in it when I was a kid.