From the other side, you can see how my knee has penetrated all the way to the other side. Also notice how my bottom leg is laying on the mat away from his knee. This space is important later when I want to chop out his knee.
Now I pull him forward to break his balance and lift him with my shin. But there's more to this than you may realize -- I know there is more than I realized. Most people will just pull down into themselves, with their elbows going down to the mat. This is weak for two reasons: that just pulls their weight down on to you and your elbows hit the ground before they can generate much power.
I train with a brown belt codenamed Mean Jeff whose number one sweep is the scissors and has been for years. Having been on the receiving end of it several thousand times, I can tell you that he'll make you do airtime and flip over before hitting the ground, not just fall sideways as you do in drilling.
While teaching a class on nothing but the scissors sweep, Jeff showed how he does this. When he pulls them, he actually tries to bring his elbows over his head, like he wants them to fly over him. He said its like how judoka do kazushi for throws. The movement is what a Raspado, a purple belt in BJJ and green in judo, calls "looking at your watch", where you bring your wrists up to your face.
When you do this, you'll feel their weight come off their legs, making them really easy to scissors now, since their center of gravity is no longer resting over them.
From the side, you can see how I'm doing "judo elbows" on him and taking his weight off his legs.
My bottom leg chops out his knee. When I do this, I make sure to slide it along the mat and hit them at the very bottom of their knee. Some people have a habit of lifting this leg and chopping them at the waist, which doesn't take out their leg.
Twisting my hips to come on top.
Now in mount. Notice how I'm still holding the same collar and elbow grip. You can use this to take an armbar in the last photo instead of mounting, but that's for another day.