Hey there, all really decent stuff there. I'd really recommend the Animator's Survival Kit. It's a fantastic book from Richard Williams and it shows you some excellent ways to do the bouncing ball, walk cycles and 4-legged walk cycles, amongst others.
If I could pick on two things, it's that when the ball falls, it goes too thin for the size of it. If it goes that thin, it should stretch up further so it looks like it has the same mass, just elongated. For the room it is bouncing in there, I'd have made it a little fatter, but the easing in and out worked well, and the squash at the bottom was really good. Gave a really nice impact. Second thing is your Day 7 piece, the tentacles, again - if I was to be doing it, would contract in a bit to reflect the ripples/waves of them.
So if _ turns into ~ the length would shorten due to the bends, but the area would still be the same. It's just because the bends are pulling the end of the tentacle in slightly.
Minor things, really. But they don't take away how well you've done, so don't worry. Can't wait to see some more from you!