World's biggest piece of chalk set world record by Bishop Canevin Students

World's largest piece of chalk sits in Joseph Romano's classroom at Bishop Canevin High School, crumbling ever so slightly on one side.

Mr. Romano likes to write with big pieces of chalk, such as sidewalk chalk, much to the enjoyment of the 11th-grade students in his AP U.S. history class.

One of them, Nick Sylvester of Kennedy, decided to joke with Mr. Romano about making him an even bigger piece of chalk for extra credit, and the project to create the world's largest piece of chalk was born.

Typical blackboard chalk is manufactured from gypsum, which is a kind of calcium sulfate. Sidewalk chalk is also manufactured from gypsum, but it can be made from plaster of Paris and water, the method Mr. Sylvester chose.

Mr. Sylvester wanted to make the chalk in a 32-gallon trash can, and so he purchased enough plaster of Paris to fill the can more than halfway up. He bought 125 pounds of plaster from Home Depot for around $60.

Working with classmates Matt Durbin of Robinson and Terry Dougherty of Crafton, he mixed the plaster with 14 gallons of water in the trash can.

It took them about 15 minutes to adequately stir the mixture using a golf club and a metal rake, and it took three days before the mixture set.

The chalk is white, weighs about 270 pounds, and looks much like a normal piece of chalk except for its unusually large size and the patterning caused by grooves in the trash can.

"[The chalk] writes and everything," Mr. Sylvester said. "But it's 270 pounds, so it's pretty hard to write with."

To overcome that problem. Mr. Romano has been breaking off bits from its side, which has diminished the chalk's size a bit.

The boys said the chalk also lost some of its weight when it was removed from the garbage can. They cut the chalk from the garbage can, and as they were doing so powder came out and some chalk residue remained in the can.

Even so, they think they have created the world's biggest piece of chalk, and Mr. Sylvester recently submitted an application to Guinness World Records. Since there currently is no record for the world's largest piece of chalk, Mr. Sylvester completed an application for a new Guinness World Records category.

He said he doesn't yet know what he'll have to do to prove he has the world's biggest piece of chalk. According to the Guinness World Records website, it usually takes four to six weeks for the organization to respond to a record-breaking application.

To compensate for their time and effort, Mr. Romano will give the boys 15 to 20 extra credit points. Meanwhile, the chalk has found a permanent home in his classroom.

"I'll probably chip away at it," Mr. Romano said.
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