Do Now:3/24/09

Just the day ago I saw a rock float at my grandmas house, of course it didn't float in the air its not possible yet? Well anyways a rock with many holes I think it was called a porous I put in a bucket of water and it floated I guess the buoyancy was greater than its weight it was a good experience I got so excited I took it it was also very light and chalky so I used it like chalk on the sidewalk.