TULSA, Oklahoma - Tulsa Public Schools broke ground Friday on a new school library, with a ground-breaking construction technique: Tornado-proof glass for the windows. T

he work is underway on an expansion. The district needed more space, wanted a safe room and came up with a way to build a library with windows that can stand up to a tornado.

TPS broke ground on a $2.9 million expansion for Mitchell Elementary that will create eight new classrooms and a 2,600-square foot library that will double as a tornado shelter.

Like most old school buildings, at Mitchell, the hallway is about as safe as anywhere else, but it has lots of doors and windows that cannot take high winds. The plans for the new library look conventional, but there's something different.

There's lots of glass that's bullet- and blast-proof, able to withstand wind up to 250 miles per hour.

"They're very expensive, but they will withstand anything that's thrown at them in a tornado," Trigon project manager Tim Mayer said.

The reinforcement added about $300,000 to the overall cost. The Moore tornado has put a new emphasis on shelters for schools. For Tulsa, every major new project will include a shelter for as many students as possible.

"A library is a good size to hold the entire population of an elementary, so whenever we're adding new libraries, especially," Bob LaBass said.

The problem is size at high schools, where there's so many students, that making new buildings tornado proof would add millions of dollars to the cost. Instead, schools like Memorial will have safe places for smaller groups.

At Mitchell, the new library will be the ultimate safe place for children, and their librarian, Katy Blair, thinks that's a big step.

"Not all of our kids are the best readers, so that can be very challenging for them, and if we make this place safe and inviting, it removes some of that anxiety," Blair said.

Another tornado shelter library will go in at Lindbergh Elementary School. These two will be the first above ground, safe rooms with windows that are built in the district.