Closed guard, bottom
Scissor sweep

Usually the first sweep you learn. Your legs work like the blades of a pair of scissors: one shin across their belly, one leg chopping their knee, while your grips pull their weight over the top.
Step by step
Grip sleeve and collar
Take a deep collar grip with one hand and grab their opposite sleeve with the other. The sleeve grip decides which way they'll fall.
Shrimp onto your side
Open your guard and hip escape so you're on your side, facing them at an angle instead of flat on your back.
Shin across the belly
Slide your top shin across their belly with the knee blocking their far hip. Keep the foot hooked on their near hip.
Chop the knee
Drop your bottom leg to the mat behind their knee, on the same side as the arm you're holding.
Scissor and pull
Pull them forward onto your shin with both grips, then kick the top leg over while the bottom leg chops back. Keep the sleeve so they can't post.
Come up in mount
Follow them over and land in mount, still holding the collar grip.