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Green Kid Crafts is $19.95 a month + $4 shipping. Less if you sign up longer. Each Box contains 4-8 Creativity and STEM Science Kits, extension activities, and free online extras. They have Junior (ages 2-4) & Discovery (ages 5-10+) options.
Use coupon code GET50 and receive 50% off your first month.
You can check out the options here.