In our advanced kids program we have the kids do specific drills for their warm ups as opposed to just doing random exercises. This is more productive in our usage of their time. The techniques they drill become second nature, requiring no thought, just reaction.
...
https://www.youtube.com/watch?v=dFoTfvGxTbg
In this video we attack with four variations of the hip bump sweep which will result in either the sweep or a triangle choke.
...
https://www.youtube.com/watch?v=lDoTf-XtDJI