Found this on io9 and was blown away by it:
Eerie Chalkboard Drawings Show Life In Oklahoma Schools 98 Years Ago
From the article:
Contractors doing construction at Emerson High School in Oklahoma City unearthed chalkboards from 1917, showing classroom life from 98 years ago.
In making way for new white boards, the contractors removed chalkboards only to find another set of chalkboards — with the preserve writing and illustrations — underneath. It looks like the 1917 lessons were covered up during Thanksgiving/Christmas break, since every classroom had a lesson on the Pilgrims in it. And at least one classroom was counting down to Christmas.
Of the images found on the old chalkboards shown in the article, this is the one I found the most fascinating:
Some kind of multiplication aid, I imagine, yet one for the most part lost to time. A comment below the article offers an idea of how this particular aid works, but I’m lost!
The original article, along with an equally fascinating video, can be found here: