The scissor sweep is an all-time classic move in BJJ. Start with your partner in your closed guard. With your right hand in their cross-collar and your left hand gripping their same-side sleeve, open your guard up by planting your right foot on the mat. Hip out to the side, and slide your right knee across your partner's torso, leaving your foot hooking their left ribcage or hip area. Take your partner's weight off the mat by pulling them forward, and you should be able to "chop" their leg out from under them while you push their torso the opposite direction, hence the "scissor" term. Try to finish in the mount.