Is this Solar System Sidewalk Chalk Set the greatest arts and crafts gift in the galaxy? We think it might just be. First of all, it includes 9 round chalk pieces inspired by our solar system's planets (plus one extra for our old pal Pluto). Inside each piece, you'll find multiple colors meant to represent the cores, layers and crusts of the planets. And the whole set is biodegradable, including the recyclable packaging, so it's good for our home planet, too. What's more: this classic kids' art supply makes for a thoughtful gift.