They offered instrumental music at the schools I attended from the 4th grade on. I was going to do it in the 4th grade but I ran my right middle finger through the band saw in our garage shop at home, so I started in the 5th grade instead. I chose the tenor saxophone. It was a good choice, I still love the sounds the tenor sax can make.
I was never a real musician, no more than a person that learns to type is a writer. If you are really a musician, you learn to identify musical notes with the sounds that they represent and with the fingering and omishure on the mouthpiece of your instrument that is required to produce the sound. If you're a real musician, if you hear a song in your head, you can either play it on your instrument or write it down in musical notation. I could never do that. I wish I could have. I played the saxophone like a typist copies a manuscript page.
I would have been better off learning to type.
I did learn to whistle pretty good. If I heard something or made a song up in my head I could whistle it. I didn't know what the notes were and couldn't write it down but it's better than a lot of people can do. It's true, there aren't that many competent whistlers. It's the same with singing. Everybody thinks they can sing but just listen to them sometime. It's not really happening for them.
Teaching music must be a profoundly frustrating experience. Every music teacher I've ever met was a drunk, if they were lucky, otherwise they were crazy, had anger management problems or sexual perversions. It's because they were people who had musical talent and spent their entire lives trying to communicate it to people who mostly don't. I'm sure it's Hellish.