I've wanted to know what sort of "warm up" drills the kids do. In some videos I've seen, the teacher instructs or talks about doing a drill or drills, but no one has ever put a drill on youtube or written down a drill. These kids would work through their drills to build speed.
This girl is using an older style 1/5 soroban-the bottom five beads were reduced to four beads in Japan in 1938. The extra earth bead might make subtraction more efficient. The extra bead is not used in this drill exercise.
Drill is 1+2+3…….+100 which equals 50x101.
http://www.youtube.com/v/VisGOjfPRKI&rel=1Chris.