Artemis BJJ (MYGYM Bristol), Can Sönmez, Bristol, UK - 23/09/2015
When it comes to the stiff arm escape, I find Marcelo Garcia's elbow push (technically it's the triceps, but he calls it 'elbow push' on MGinAction) is the highest percentage option. He works from under a standard side control then brings their arm across. To do so, make some space by pressing into their neck and bridging if necessary, then sneaking your other hand under their armpit and onto your head.
Use your elbow to bump their arm over, bumping it up high on your head. As soon as their arm clears your head, immediately grab just above their elbow, pinching your hand around their triceps: you can support this with your other arm if necessary. Extend your arm so it is straight: this is absolutely key, keep it straight. Still holding their arm, swing your legs up, then as they come down, use that momentum to sit up. Bring your free arm backwards in order to base out on your elbow (if possible, extend that arm when you can, in order to post on your hand and create a stronger base).
As Jeff Rockwell points out, you need to sit up high. Otherwise, they can just walk their legs around to the other side and re-establish side control. If your body is in the way, they can't (if your legs get stuck, Rockwell suggests a quick hip bump to free them. You might also be able to switch to the more ambitious option of driving them all the way over to their back). Continuing to push on their triceps, shrimp backwards into the space you've created, until you can recover guard.
Sometimes you'll be able to combine this with the other option, which is to keep pushing into their elbow or armpit until you can roll them over. Normally it's easier to shrimp out to guard, but sometimes their weight distribution means that pushing them over makes more sense. Another handy detail from Rockwell applies if they manage to sweep their arm back. Immediately switch your arms, changing direction to push into their biceps, shrimping out to recover guard.
Teaching & Sparring Notes: This went ok. The question is if I should teach it when they already have the cross-face and show how to clear that off the head, or if it is better to go for the easy version. So, they are in the process of passing their arm over to move into north-south, which is when you catch them. The latter would have the advantage of focusing on the core of the technique (the stiff arm and sit up), but the former puts it in a more realistic context.
Sparring from side control, I was too high on Ross. He was eventually able to swivel out, bumping and making good use of his legs too. I was finding I had to chase a bit, putting arms in the way. Goes to show I can't be as lazy with more experienced students now!