Ever since they were little I’d have lots of conversations about kids in poorer countries do for fun instead of buy things. Then we’d look up stuff about other countries. And always commented on the lifecycle of things and how much people buy just to buy. I also took them to thrift stores a lot to see the stuff that was just for sale at a regular store didn’t make that person happy and now it’s here. It wasn’t an instant process but rather a long childhood conversation. This book was a staple in our house. https://www.amazon.com/Material-World-Global-Family-Portrait/dp/0871564300
I can't tell if anyone has already posted this, but there's an interesting book called The Material World that does the same thing with families around the globe. Each family poses for a photo with all of their possessions and pets. It was published in the mid-90's and it was eye-opening to me when I was a kid.
Peter Menzel has a similarly themed earlier book, Material World. The photographer's gallery is online.
WinterPromise (https://winterpromise.com) has a themed Homeschool curriculum and we used Children Around the World. It’s aimed at 2nd-6th grade but we made it work at a younger age. It covers some history, culture, geography, art, traditions and holidays. I think the reason my kids liked it was because many of the things they learned about were through the eyes of the children in each country. It is Christian but the Bible/journaling portion can be worked around. I want to mention my favorite book, Material World: A Global Family Portrait (https://www.amazon.com/Material-World-Global-Family-Portrait/dp/0871564300/ref=sr_1_2?dchild=1&keywords=material+world&qid=1598123080&sr=8-2) which documents through photographs what an average family in different countries actually owns in material possessions. Coloring maps, reading stories, doing art projects, and trying recipes was fun. This book really brought home the reality of what it is like to live in other parts of the world.
Material World: A Global Family Portrait? link