The child has filled the clear plastic tube with snow. He has placed on the incline. His right hand holds the tube down onto the incline. He uses his left hand to manipulate the snow in the tube. He lets the snow drop partially out of the tube and pushes it all back into the tube. With quick motions, he lets the snow slip out of the tube ever so slightly and gently pushes it back in. As he does that, the snow seems to slide in the tube more easily. He then lets the snow drop a quarter of the way out of the tube and then gives it a harder push so the snow travels further up the tube. He repeats with a smaller drop and a smaller push. Now he lets the snow drop halfway out of the tube and gives it a bigger push yet. Finally he again lets the snow drop halfway out the tube and gives it a big enough push that the snow is launched out of the tube.