Artemis BJJ (MYGYM Bristol), Can Sönmez, Bristol, UK - 25/11/2016
The situation is therefore that you've already got into the crucifix, with their arm bent around your leg. To make things easier (and safer, for drilling), I am assuming they have already grabbed inside their own leg to prevent you getting the arm. Base out on your far arm, then do a tight roll over your near shoulder, similar to breakfalling. You aren't looking to travel forward much with that roll: attempt to roll underneath yourself.
As you roll, reach your near arm under their shoulder, aiming to grab their near leg. Continue the roll, making sure you still have their arm and leg trapped. They will normally roll too, due to the pressure on their shoulder. Be careful, as if you're too explosive you may put excessive strain on their shoulder: stay controlled throughout your rolling motion. That roll should result with you in an upright position, while they are lying next to you.
It's essential that you still have both their leg and their arm trapped. Wrap your arms tightly around their leg, then switch so you have your outside arm around their leg. The elbow of your inside arm goes into their far armpit. Keep leaning into them throughout, keeping your leg tense so they can't unbend their arm or pull it free (if they do, you still get side control, a pretty good consolation prize).
Base on your far leg, keeping your near leg closely wrapped on their arm. Assuming you have managed to keep their arm bent with your near leg, use the base from your far leg to keep bringing your hips back. You then tilt slightly, to bring your bottom leg underneath you. This should eventually torque their arm to the point that they tap.
Teaching Notes: Doing this as a follow up to the dog leg armbar works well, which checking my notes is what I did last time I taught this two years ago too. This takes longer to teach, so that's important to keep in mind in terms of warm-up length. I added breakfalls to the warm-up, to help with that rolling underneath yourself element. People were ending too far from the leg, so I'll emphasise hugging it. Others were losing the arm as they rolled through, another thing to point out (although if you end in side control, not too bad).
Aesopian had some good tips on Instagram, specifically on being too far from the leg: "A tighter and deeper hug on the leg fixes that. Try to get your head next to the knee even if you have to shoulder walk." Final thing to emphasise is the finish: it isn't just scooting back, you're also raising your hips to tilt, bringing your leg underneath you.