Thanks for taking the class! I hope you now have some more buttonhole “tools” in your Crochet Toolbox.
Here are some other resources you might find helpful:
The Simflex Expanding Sewing Gauge is the nifty tool I had in class. That link is to the best price I could find at the time, but you might poke around Amazon to make sure you find the best price.
CGOA Chain Link 2018: I’ve emailed you the corrected p. 3 of the handout.