How Many Times Do I Have To Tell You........

Zits Comic: Jeremy walks into the kitchen where a huge calendar is on the wall
Jeremy: What's this?
Mom: It's a family schedule board. This will be a place you can come to for reminders, appointments, lists and general information of any kind.
Jeremy: I thought that's what you were for!
Like Jeremy, your teens are probably mom dependent! Somehow you become that person of blame when a practice or rehearsal is missed, or a music lesson, or haircut even though you have a very distinct memory of reminding your teen just that morning of said practice, lesson or appointment. And now somehow, it has become your fault that they forgot it. Isn't it always that way? You never get credit for the good stuff you are responsible for, but get sh** for the stuff that is really their responsibility.
Family calendars in theory are a great idea, especially if you have several children. But their effectiveness is more about keeping your head straight about who is going where and when than for your kids. They can open and close the refrigerator door a thousand time, and never once glance at the schedule. After all, their head is filled with way more important things as they mindlessly survey the contents of the fridge. That big board is just filled with alot of useless letters and words.
So you have a choice. Let the calendar speak for itself, and declare yourself off duty as the schedule master. If you stick to your guns, your teens will learn by default that the responsibility of keeping track of their lives will fall to them. Natural consequences like angry coaches or piano teachers might yield a change in behavior. Or, you can keep the schedule in play for youself, and find better strategies to remind your kids about what is coming up. Just saying "don't forget...." is not a strategy. In the moment they hear you, but in the chaos of their brain, as soon as a thought with more importance pings, your reminder is long gone. Develop a system together, a text message, a note on their steering wheel if they drive, an alarm set on their phone. Be creative, like dogs who salivate when they hear the can opener, and know that food is on the way, so can your teens be trained. Just get creative!