Start by reading The Longest Day: Celebrating the Summer Solstice
After the story, get active by practicing Sun Salutations, a series of yoga poses that help us honor the sun while stretching to increase flexibility and strength. You can follow along with the poses on the free, printable sun salutation poster from Childhood 101, or you could try moving along to the words of Kira Willey's song, Dance for the Sun
Next you can create sun prints using a few supplies you may already have on-hand and the copious rays available on the sunniest day of the year. Head to Tinkerlab, where Rachelle Doorley provides all the simple steps for this fun, sunny-day craft. If you enjoy this craft, you should check out Doorley's fantastic book, Tinkerlab: A Hands-On Guide for Little Inventors
If it's not too hot too turn on the oven, you can make a celebratory sun cake.
Start by baking your favorite cake recipe (or box mix) in two round pans. After they're baked and cooled, lay one round cake in the center of your platter. Then cut the second cake into equal wedges by cutting in half and then in fourths and finally in eighths. You can trim the round edges off your triangles to make them fit better, and then arrange them around the circumference of the circle. Then frost the whole thing in yellow or orange frosting.
You can get the cute summer pineapples pictured above from My Sister's Suitcase.
If it feels too hot to do do any baking, you can turn mandarins into festive sunshine snacks using the printable suns from Studio DIY.