Looks like it may be a 1979 Emerald Green COLLEGIATE.
It has the "you can shift without pedalling"- Shimano Front Freewheeling System.
These worked well and eliminated the confusion about how to shift gears for anyone who was new to bicycling.
The so called serious bikers of the day made fun of it, just as they had been doing to everything electroforged from the Windy City, but they (serious bikers) would later benefit from the Shimano index shifting which evolved partially because Shimano had developed the FFS earlier.
The Shimano FFS was a good product for a lot of riders.
That is a great looking Emerald Green Collegiate. Schwinn got that color combination absolutely perfect with the late day graphics,....it is a beautiful bike!