In class last week we discussed the following best selling children's book, The Number Devil: A Mathematical Adventure by Hans Magnus Enzensberger. 

It is a chapter book containing colourful illustrations of various mathematical discoveries. 

It's a best seller, so I think you'll enjoy reading it, and your students - particularly your elementary students - will find it engaging and entertaining. 

I wouldn't limit it to just elementary students at all as it makes a great whole class read-a-loud. It will depend on your students of course!