While preparing rooms for renovations, workers at Emerson High School in Oklahoma City, Oklahoma uncovered something they didn’t expect. Usually, they find broken pipes and wires but this time they uncovered chalkboards from a century ago, still bearing the lessons and drawings from children and teachers, reports Tim Willert for The Oklahoman.

The Oklahoma City Public School District posted pictures of the preserved chalkboards to their Twitter account. A spokeswoman from the district says that they are looking into ways to preserve the finds, which according to some of the writings, dates back to 1917, reports Elahe Izadi for The Washington Post. ​

Stuck in time. Drawings from 1917 uncovered during MAPS renovations at #Emerson pic.twitter.com/QDd2IlL3Sx — OKC Public Schools (@OKCPS) June 5, 2015

A calendar and a dated note place the lessons in November and December of 1917. Nearly every classroom had lessons on pilgrims, Izadi reports for The Post.

You find a lesson on pilgrims in every classroom. There was #aligned curriculum in #1917. pic.twitter.com/MurjKd8n6i — OKC Public Schools (@OKCPS) June 5, 2015

In clear cursive script one of the boards has some partially-erased phrases: "I give my head my he… and my life to my God and…" and "one nation indivisible with… justice for all." Another carries the inscription of "R.J. Scott, Dec 1st 1917, Emerson Janitor." Music lessons, colorful drawings of a bird, a turkey, a girl in a pink dress, a log cabin and a ship sailing on a blue sea survive on other uncovered chalkboards. There’s also a list of names.

English teacher Cinthea Comer was impressed by a drawing of a blonde girl in a blue dress with pink collar and sash, blowing a bubble. Workers found it in her classroom. “It was so eerie because the colors were so vibrant it looked like it was drawn the same day,” she told The Oklahoman. “To know that it was drawn 100 years ago ... it’s like you’re going into a looking glass into the past.”

Music lesson from 1917. pic.twitter.com/bVRqU2hmT0 — OKC Public Schools (@OKCPS) June 5, 2015

The old blackboards are made of slate and were hidden behind newer blackboards. Workers had removed the existing boards off the walls, revealing the history behind, in order to "make way for Smart Boards, interactive whiteboards that use touch detection for user input," Willer reports in The Oklahoman.

More photos by Doug Hoke of The Oklahoman are at the paper’s website.