Artemis BJJ (MyGym/Bristol Sports Centre), Can Sönmez, Bristol, UK - 11/02/2015
The first rule of the back position is protect your neck. There are lots of ways of doing that, but my preference is the Saulo Ribeiro method. One hand is in your opposite collar, the other hand floats, ready to block their incoming grips. Don't reach too far with that arm or you'll leave space: keep it near your chest. Your elbows are inside their knees, ready to pop off their hooks if the opportunity presents itself.
Next, bring your knee up on their choking arm side (so, the arm that is reaching over your shoulder and trying to wrap your neck, rather than the arm coming under your armpit). Angle your knee inwards, to prevent them from rolling you back the other way: they will find it easy to choke you if they can roll you in the direction of their choking arm. In one quick motion, move your head forwards and simultaneously shove their head sideways (this is presuming they know what they are doing and have their head tight to yours for control). Look towards them, keeping your head and neck firm in order to stop them moving their head back into place.
Push off your leg and bridge back, aiming to get your shoulders and spine to the mat. If you aren't able to get your head past theirs, still push off your leg. Put your head on the mat and then grind it underneath their head. This isn't pleasant for either of you, but it is generally effective: preferably you can get your head past theirs in the gentler method above. If you can, clamp your arm that is nearest the mat to your side, aiming to trap their arm. To really immobilise them, see if you can use that same arm to grab their opposite sleeve/wrist, meaning you're using one arm to control both of theirs.
With your near arm, grab their trousers by their top leg (either by the knee or a bit lower). When you have the opportunity, switch to grip with the other hand. There are several options at this point. I like to either reach across their neck and grab the gi, or better, reach under their head, grip the far armpit then lock my shoulder into their head and shoulder. Either way, push off your free leg and turn to try and come on top. With your grip on the knee, stiff-arm so they can't lock their half-guard (if they do lock their half guard, this puts you in the opposite side half guard pass position, so proceed from there). Free your leg (pushing on their leg if you need to) and move into side control.
Teaching Notes: When I previously taught this in the women's class, I was worried it was too complicated. Now that there is a core of women who have been training for a few months, that's less of an issue. As most of them have also been training in the mixed class, that all-important frame of reference is hopefully starting to build.
I think it's very important to know at least one back escape, plus I also want to teach something I'm confident is functional. The Saulo scoop is easier, but I have pretty much never used that in class because it's so rare that someone will have back control without some kind of upper body control (at least in my experience). I think everybody got the general idea, but the difficulty that cropped up a few times was the turn to the top. Getting out of the tight arm grip caused problems: it is something that I think can mostly be solved by learning how to put your weight onto them, driving off your legs.
However, like much of jiu jitsu, it's not an intuitive movement, so I need to work out a drill to help make it more familiar. A balance ball is the first thing that comes to mind, but I don't think there are enough of those around the gym to do it. I could give it a try next time anyway, though. Or some kind of two person drill for that, like the side control one where you swivel around to the other side maintaining pressure.