Artemis BJJ (MYGYM Bristol), Can Sönmez, Bristol, UK - 22/04/2015
The situation for this is that they have stood up in your closed guard. As they stand up, if you've got a grip on their collar or head, maintain it in order to keep their posture bent forwards. At the moment you let go of that grip (if you have one) and they try to reach an upright position, grab behind their ankles (around the outside: if you grab around the inside, there's an injury risk).
Open your guard (when they stand, they are looking to open it and pass. It's better if when you open your guard, it's on your terms rather than theirs), bringing your knees together under their chest. You can also put your feet on their hips, depending on their height and how much leverage you need. Either way, drive those feet or knees into them. That should knock them over if they aren't prepared for the sweep.
Before they can react, come up on your hand and same side knee, then bring your hips forward on that same side. It's important you don't try to move straight forward: your direction must be diagonal. Slide your knee on that side to the mat, keeping your hips low, also grabbing their head. From there, you could go to mount, s-mount, side control etc. It is an awkward position, so takes a bit of getting used to. I used a hip thrust drill during the warm-up to help: you can do a technical stand-up from here too if you find that easier, keeping hold of their leg and passing around to the side.
Teaching Notes: I forgot to emphasise grabbing behind the head to help pull yourself up, must do that next time (though Summer was doing it instinctively, which was cool). Also, on the technical stand-up version, staying tight, driving forward and really pulling up high on the leg. I included both versions, which this time seemed to make more sense to the students. They had trouble with the technical stand up last time (a few months back), but this time round I think it may have made more sense than the hip thrust, as that can be a bit awkward (though the head grab helps). So, worth keeping in both versions for the moment.