Simple Unit Intro and involving other classes: (wedge) A nine hole miniature golf course made from cardboard boxes. A great way to keep kids entertained while they are stuck inside and a fun way to learn about physics.
I can see making one table and then having a number of bins - cloud sand, colored rice, beans, water, etc. Just keep 'em stacked in the garage and switch out as desired. Cute idea for a water table too.