I came across some books that some of you may already be familiar with:  Loose Parts:  Inspiring Play in Young Children and Loose Parts 2:  Inspiring Play with Infants and Toddlers, both written by Lisa Daly and Miriam Beloglovsky, with gorgeous photos by Jenna Daly.

The books are lovely reminders, beautiful to look at, of how fundamental play is for children, and full of simple and easy-to-obtain suggestions of materials that you can use to intentionally support their development by having them available for them to explore.  The books hone in on the importance of letting kids explore and problem-solve, and setting up an environment that allows for that.  They also give examples of things teachers/caregivers have done to support and challenge kids to try more things. 

I highly recommend taking a look at these books!  Whether you consider using loose parts in your play areas, or think about how to use them in play groups, story times, or other programs, there is a lot of potential for awesome exploration and fun.