We've been doing a lot of Outer Space things recently.  One day we were reading a book about Saturn (because seriously, what kid's favorite planet WASN'T Saturn?).  In the book (Exploring Saturn; Bartolotti, 2003), there was a section that mentioned that Saturn is the size of approximately 760 Earths.  This book is clearly for older kids (like 4th or 5th grade) and had a LOT of information in it, but my 4.75 year old insisted on getting it from the library and insisted on reading it, so I did a lot of paraphrasing and skipping stuff that was too abstract.  But this particular piece of information seemed to stick with him and he of course wanted to do a project about it.  We together brainstormed what we could do, but it had to wait for another day, because clearly this project was not going to work with my two year old and his two year old friend hanging around.

First, we counted out 760 pinto beans (now you see why having the two-year-olds around was not going to work).  We did it by making 76 piles of 10, and then I showed him how we can count by 10's.  He caught on and joined in the counting.  There is no reason why it had to be pinto beans.  They just happened to be the oldest beans in the back of the cupboard and weren't organic (we were not going to waste the more expensive organic beans).

I also had him write out 1 = Earth,  760 = Saturn.  It was good writing practice and he was willing, so we went with it!

Then for the fun part.  While you can see from our display of beans how much more 760 is from 1, it doesn't quite translate to the size of the planets.  So we got a balloon and filled it with 760 beans.  This is not an easy task.  I ended up using the adapter cylinder from the Kleen Kanteen sippy cup to hold the opening of the balloon open, and had to keep blowing it up a little to make the beans settle to add more [A funnel would probably work better, but we don't have one.].  But finally, all the 760 beans were in and we tied off the balloon and added a pipe cleaner (because Saturn needed rings!).

I would also recommend double bagging Saturn, since ours had an unfortunate accident resulting in needing to fill a second balloon.  I double bagged Saturn after that and did a better job making sure the pipe cleaner wasn't poking it, and it's thankfully remained intact for a few weeks now.  It even survived a trip to preschool for share day, where he further impressed his teacher by explaining the whole thing AND added that Mars was the size of half of Earth, which meant it was half a bean.

I LOVE what hands on learning can do.  He really understands the size difference now, and is noting size differences everywhere now.  And this is an early intro to fractions as well with the concept of "half".