Make one special photo charms for your pets, compatible with your Pandora bracelets. Rainbow Cupcakes with fluffy cloud-like vanilla frosting that is guaranteed to make anyone who sees them smile. No cake mix, still EASY.
Could have the kids do this, upload to Edmodo, and then include a write-up explaining the different phases. Hands On Science: Phases of the Moon Activities for Kids - Inspire Creativity, Reduce Chaos & Encourage Learning with Kids