Back in the (pre-internet) day…
Parents bought their school-age children an encyclopedia to help with home work/book reports etc. They were a bit pricey, and for some it was a real luxury to have a set on the shelf at home.
My parents bought the 1975 World Book encyclopedia for me and my siblings. In 1975. When we were kids.
They are now essentially worthless. Old sets are donated to thrift shops and libraries all the time.
But you should have a set in the art room!
You see, some things never change. Cats look like cats, the same as they did in 1975. Open the World Book Volume C and you will see tons of breeds of cats on a single page. Kids love this!
Take that volume back to your seat, kid. Draw the Abyssinian cat.
What does a lighthouse look like? Go get Volume L. A skeleton? Volume S. You get the picture.
Sure, I could look them up on the Google images. But I have only one computer, and I have a whole set of World Books.
If you run across a complete set at a thrift shop or garage sale, grab it! Or better yet, let your colleagues/friends/neighbors know you would like a vintage set. Someone in your town is surely cleaning out the attic this weekend.