Kids need to be taught that their planet is precious. That nature takes time to grow or to heal after we wasted it. My sons pick and grow their own vegetables, I showed them how it's done. A carrot takes three months to grow and three seconds to eat. It's a lot of time to mature and it's gone in a moment.
We planted a lot of trees too. I showed them how to collect the seeds and plant them. How to nurture and care for the plant. When the trees had grown for two years we planted them on their grand-father's land. Most of them were eaten by the deers... But some of them will become mature trees if nature is good with them. It's a lot of work, for small results, but in the long run, it's all gonna be worth it. We still have one of those trees in our backyard, it's been four years now and it only reached 18in.
Nature takes time... It's so important not to waste it away.
Teach them and show them, when they'll see it they'll believe it, and then they'll love it and treasure it!
Have a wonderful Earth Day! Go and do something green today!