The Calder Foundation Website. Click on CONTACT then scroll down to TEACHING GUIDE for a great script and explanation on how to talk to children about Calder’s work with sculpture. Images of his works can also be found here.
The National Gallery of Art has a Calder virtual tour online. It’s meant for an individual to work through but if you have time before teaching this lesson, it’s worth taking 15 minutes or so to familiarize yourself with Calder’s wide body of work.
The Whitney Museum has a few audio guides and a video on Calder’s Circus. They are both fascinating. You can download transcripts from here as well.