I kind of remember my daughter's first official word -- it was mama or dada, I'm not positive -- but I definitely remember her first eco-friendly word. It was compost. We were cooking together, and I was gathering scraps to chuck into our countertop compost bin. She grabbed a handful and held her fist over the bin and asked, "Mama, compost?" to ensure that the peelings and ends were not part of our dinner. I said yes and proudly watched her stuff the bin with carrot bits. I was proud because she had picked up the word on her own. I hadn't specifically taught it to her. Apparently I used it more than I thought.
That usage is key. It's [obviously] how children acquire language. They begin by hearing words. This is why it is so beneficial to read to your children. This is also why it is beneficial to use a lot of words, and introduce new words at every opportunity. My daughter speaks eco because I spoke it to her. I differentiated throwing something in the garbage versus recycling. I told her we must conserve energy as I switched off lights. I discussed how we compost our produce instead of throw it out. She picked up on the nuances of these words. This is not amazing. But it is meaningful.
I could've called the compost bin the garbage can so she understood immediately what I meant. I could have told her simply to turn off the lights. I could've called the recyclables trash. But I used the lingo automatically, so that is what she learned. Simply by using the correct vocabulary, she is learning about responsible environmental practices. I love that. I wasn't even thinking about teaching her about being green, but the lessons began on their own.