Fan of sports
"Anyone have any other options for increasing the knowledge of parent/spectators of soccer matches?"
One thing that I do in the 5-15 year old ages, when I ref is communicate. I go to the touchline and introduce myself. I explain safety/fun first. What is advantage/play-on,offsides. It takes a few minutes and the parents like the connection. At the half I walk over again and ask if there are any questions. I have had some and crazy as it sounds a few times they have given me a poweraid "I check to make sure it is still sealed".
Granted this is grassroots and may not be allowed at HS level. But do it enough down there and we all will be informed.