a few more ideas to get your research juices flowing... Kindergarten Eye Chart is too young for your child, or you want a piece with more longevity, you could also opt for the original Snellen Eye Chart:
Old classroom posters are great from a purely aesthetic perspective, but the themes of some posters still resonate. This WWI poster promoting Victory Gardens is newly relevant today:
Vintage textbooks are a great resource for affordable frameable artwork. Arachnids may not be to everyone's taste, but we can see preschoolers and up loving some framed pages from this 1941 Science Book on Spiders, available at the Etsy shop Snippets of Time:
Searching eBay using the keywords "vintage textbooks" yields tons of results, too, such as this 1960s reading primer (For some reason we love that this is the teacher's edition. The forbidden fruit!):
And while we're not suggesting you traumatize your child for life, we had to show you this vintage safety poster purely for the tongue-in-cheek factor:
When it comes to vintage artwork, really the only limit is your creativity and your ingenuity in sourcing unusual stuff. If you've scored some really fresh, original vintage stuff, please let us know!