Scale of the Universe objects. I always love these things and they're great to show to students to start all kinds of conversations.
But I simply love that they put the size of the Minecraft world in this one. If you're in a school with kids (mostly boys, interestingly enough) aged 3rd grade and up, you probably have some Minecraft players. Whether you know it or not!
So maybe armies of kids out there building a world larger than Neptune should be able to do more of this kind of stuff in school, right?