I started off the lesson playing the Elgar "Nimrod" Enigma Variations. Prior to the lesson, I sent the teacher an e-mail about how I was a theory major for a bit of time, and I had some technical issues that needed fixing, but throughout the 5 teachers I had in the past, none of them gave me a path to resolve them. I could see in my videorecordings that my fingers looked extremely tense.

After that, she laid everything out and told me everything. I didn't know, until this lesson, that:

You're supposed to view your fingers as hinges, and you press the keys by a lift and "grab" motion (not in the literal sense). Your fingers should feel as if they are "grabbing" the keys.

The highest point of your hand/wrist part are supposed to be your knuckles, not your wrist.

Your arms are supposed to be relaxed enough so that they feel like "wet rope" (amazing analogy, by the way). This determines how far you're supposed to sit from the piano.

The connection from your arm to your fingers should be straight, and not angled.