Demonstrates using sensing block (not touching ground) instead of if blocks to control motion, e.g. gravity. Also how to use variables. Manually pick up character and put him above the line. He will sink down to the line. Also uses the not touching ground trick to detect when to stop. Similar trick used for left and right combined: [NSBBP 00 sensing trick for key press demo on Scratch](https://scratch.mit.edu/projects/566229221/)
