Just as a little precusor... I'm a white belt and one of the smallest guys at my gym. At training the other night I was rolling with a guy that was roughly twice my size, and several times he'd just turtle up, face to floor, with his arms, head, etc all tucked in. I tried to get his back from this position but there wasn't enough room for me to hook his legs, and due to the size difference he was able to buck me off before I had too much time to work. He wasn't able to do anything offensively from this position, of course, but there didn't seem to be anything I could do to stop it either. What would you guys recommend? I was thinking perhaps there was some way to sweep him over onto his back, but I couldn't figure it out during the roll.