Artemis BJJ (MYGYM Bristol), Can Sönmez, Bristol, UK - 11/11/2016
A major subtype of the back is a position called the turtle, where you're on your elbows and knees. I wanted to cover some of the basics for maintaining the turtle, from the top person's perspective. A good starting point is a wrestling position I learned from Nathan Leverton, the side ride. You are alongside them, with your nearest knee next to theirs, your other leg out for base (but bent, as if it's straight, that hinders your ability to react to their movement). Your same side hand is grabbing their near arm, while your other hand is reaching inside their far hip.
Don't go too deep, just to the level of your wrist, also being careful to keep your elbow out of range: if they can grab your elbow, they can roll you over. To maximise your pressure, keep your head low. I'd also advise keeping your knee off the floor and leaning into them.
You can also move around directly behind them, legs in tight rather than sprawled back (that can work too, but it does potentially provide them with some space to exploit). In that position, put both hands inside their thighs, your knees pressing into their hips, staying on your toes and keeping your weight low. From there, you can switch to the side ride on either side. If they manage to start turning in either direction, always run behind them to their back. If you run towards their stomach as they turn, that can put you in their guard.
To regain the back with hooks in, insert your hand by their far hip, so the back of your hand is against their inner thigh. Drop back to the near side, using your hand as a preliminary hook. Roll them over with that, replacing your hand with your leg. To get in the other hook, you can use the Marcelo hip thrust I've shown before, hooking your legs as you simultaneously thrust into the bottom of their spine and pull back with your arms. That should give you lots of space to insert your second hook.
Teaching Notes: I could put in the Marcelo Garcia thing where you walk around behind to recover the back after you've lost hooks, but that might fit better in the maintaining the back lesson. Although it would fit here too, along with the hip thrust if you are struggling to get that second hook in. But generally, not much to change here, it's a fairly simple lesson. :)