Renovation workers at Emerson High School in Oklahoma City found more than a few rusty wires as they replaced blackboards in a class with up-to-date Smart Boards.

As they peeled away the old boards from the wall, colours and shapes began to appear. Underneath was another blackboard with bright chalk drawings on it. At first the workers saw names and dates, then colourful pictures of pilgrims, turkeys and beautiful cursive handwriting - all dating back to December 1917.

David Todd, a project manager overseeing the renovation, told The Oklahoman: “You find a lot of hidden things [during renovations], but rarely do you find kids’ work and teachers’ work like this on blackboards. This is a pleasant surprise.”

Sherry Kishore, the school’s principal, was blown away by the ‘beautiful handwriting’ - something that is now rare in modern schools, where technology prevails.

“‘The penmanship blows me away, totally,” she said. “You don’t see a lot of that anymore.

The blackboard lay untouched for almost 100 years and also contains some interesting teaching techniques, such as First World War-era times table ladders and a novel multiplication wheel that Ms Kishore was fascinated by.

I have never seen that technique in my life,” she said. “Maybe I’ve been sheltered, but I don’t think so.”

The school is now working with the district to come up with a solution to preserve the blackboards. This time round, the teachers of Emerson High School are determined that the past will not be so easily erased.