I think there were about fourty or so symbols, one for each English sound.

I was part of an experimental class in first grade. We were not taught to read the regular alphabet. They taught us what they called Initial Teaching Alphabet, or ITA for short. Which is exactly as you described here. The problem was, I learned how to read and write in ITA in first grade, then had to learn how to read and write in English in second grade! Such progress we made.