Hello. My beginner clarinets are struggling mightily with embouchure much, much more than I've ever encountered in my 23 years. It's as if they are physically incapable of playing in tune. I'm out of ideas. I've used all the analogies I know. Grandma face, firm up corners, take in more (or less) mouthpiece, make a flat chin, blow a hole in the floor, pull back of the tongue up, etc. I've talked about bottom lip being a cushion and top teeth must grip the mouthpiece. I've adjusted the angle of their horn. The bell is not between the knees and in the process checked that their head did not move with the horn as the corrected horn position. I've reached over and wiggled their barrel, proving to them that it's moving but should not. I've pushed up on the barrel (gently), thus forcing them to bite down and firm up so the horn doesn't then poke them in the back of the throat. It works but then goes immediately flat again when I let go. It's the same horns we've been using for years. No other group struggled. All of them have good mouthpieces. Some of them have 5RV Lyres. They all have good Van Doren reeds. These kids. will. NOT. play. in. tune. I'm out of ideas. Please help me.
Maybe check their air stream direction? You could have them use a pneumopro to see where they are blowing. You could also use an air can to demonstrate what fast air should look like (turn it upside down) and feel like; also unfocused air (no straw) vs. focused air (straw).
Keep trying! Most of my beginners this year have some kind of weirdness, but they're all getting it...........eventually.
Do they know what in tune sounds like? Rather than using a tuner, use a drone? To teach what “waves” are, I play a bass guitar while tuning a string and the waves are pretty obvious when I do that. I teach them to listen to the beats and how they get closer together when it gets farther away from in tune, etc.
Maybe try and work their ears? Just throwing something out there. Not trying to be snarky at all. You asked for help, and maybe this angle will help.
The absolute best thing I learned as an undergrad was this:
Place the tip of your index finger on the top teeth at the gumline. Then, have them push their upper lip into the finger, trying to push it down. It will force the corners into the correct position and flatten the chin. Have them hold the corners and then place the mouthpiece with the firm corners and flat chin.
Last year I inherited a move in who played very flat. It took a few weeks, but after reinforcing this daily with her she eventually fixed the issue. I had to continue to reinforce it all the way up to UIL but she eventually figured it out.