I had the exact same problem as a 12 year old kid, only I was in assembly where Auschwitz survivor Emerich Roth was telling us about his hardships. He stopped with annoyed patience and waited for me to silence the alarm before continuing. I don't think I've ever felt so bad.

A few years ago I missed a very important work engagement because it discovered the opposite.

The LG Nexus wouldn’t ring the alarm when the phone was set to silent.

I literally had to show it to my manager which was furious.

I remember my first Android phone would (I was not aware at the time) keep the alarms turned on even while in silent mode.

During the final exam of my calculus course, which takes place through two class sessions, my alarm went off to remind me of my second class session. Despite the professor promising to tear up our exams up if our phones made any noise or appearance the hour before, I'm assuming he ignored it because I was literally the only person in class that made any attempt at engaging with his lectures. Unrelated, I had also completely given up studying for the exam since I knew I was going to fail and had plans to retake the course (but be at least present to take mental notes on the final), but he clearly bumped me up to a minimally passing grade for what I can only assume was the same reason.

Meh, I was a mediocre Calc student and walked out of the final feeling like I'd utterly bombed it, but had the same prof for Calc II and apparently I'd managed a solid B on the final so something had stuck.