I’ve realised that I push my tongue against my bottom lip when I’m playing. I think I’m also varying the amount of pressure I apply when moving octaves and to give me different tones. After coming to this realisation I’m making the assumption that this is wrong and wondered what you are supposed to do with the tongue when playing (when your not tonguing the notes in the classical sense)?
Good question! I don’t remember seeing it discussed much. I believe what I do is keep the tongue pulled back and free-floating, so as to be available for occasional limited note-tonguing. I don’t think it’s useful to have it pushed against the lower lip, as that would add some muscle stress, and limit your ability to use it for note shaping.
Wow! That’s interesting! I do the same thing, but probably for a different reason… I am a trumpet player in my other life and I switched to Jerry Callet’s “tongue controlled embouchure” a couple of years ago. It is pretty much as you describe - the tongue pushes against the lower lip. (There’s actually much more to it, but that’s the jist). Anyway, I started flute after I had switched to this embouchure and found that I can’t really get a good tone without it on either flute or trumpet (which I still play, btw). I think if it works for you and you get a good sound, there’s no big deal.
Pat
Hi. Thanks for the responses.
My tongue seems to be in the same at rest position as when not speaking (and does not seem to change when moving my lips into blowing position). Relaxed, and with the tip just behind my lower front teeth (no pressure against the teeth).
I guess the same is true for me since my at rest position is up against the lower lip.
Gee, how’s it get past your teeth? None in front? If your tongue (the tip especially) is high enough to be against the lip, I’d be concerned that it is blocking your airstream.
I’ve never thought about tongue placement, but after reading this and playing my flute (and thinking about it) my tongue does seem to rest lightly against the lower lip. The flute is actually pressing into my lower lip making the lip protrude a bit past my lower teeth, or you might describe it better as making my teeth cut into my lower lip a bit. The tip of my tongue seems to rest against that area where the top of my lower teeth press into the lower lip.
I rest my tongue on the bottom of my mouth, behind the teeth, to keep a nice open space for the air to move. I find that having a really open throat encourages the tongue to drop and keeps it away from the teeth.
you obviously have not fallen on yer lips enough to require assistance in holding them up 
That’s really interesting and I’ve never thought of it. I’m guessing you’re told to keep your throat open if you’ve had a flute teacher? I’m totally self taught and have taught myself lots of bad habits. Do you have any tips on how to keep your throat open?
Karl.
I find mine often ends up the most inappropriate places.
That isn’t a complaint.
I have had a flute teacher (a classical one). Try yawning a couple of times and feel how open your throat is (you don’t want to unhinge your jaw, though!). Make sure your teeth are separated. Other images are to imagine a ping-pong ball at the back of your throat and to breathe in the syllable “oh”.
(Sorry this is so late…school, aaaah!)
If you use the TCE technique I mentioned above, yes the tongue rests against the bottom lip, but that doesn’t prevent getting an open throat and a good airflow. Not sure what the issue is… When I play, my tongue still flattens down in my mouth, I just have a more focused airstream.
Pat
I undid this myself many years ago by simply practicing to get a good flute tone without using the tongue to support the lower lip. After a month or so I could play without doing that, it wasn’t fun at first (like zero tone!) but it didn’t take that long to switch.
About Karl’s question on opening the throat, if you imagine singing (vocalizing) the notes you are playing, that will fix up the shape of inside your mouth. If the note’s too low or high for you just imagine singing it in the octave you would ordinarily use for that note.
I fell on my lips when I was about 8, does that count?