ALEXANDRIA — A group of students got a chance to test their engineering skills when they participated in the Rube Goldberg Challenge on Friday, April 15.

The event took place at the Douglas County Library and was named in honor of cartoonist Rube Goldberg, who drew elaborate inventions designed to complete mundane tasks.

"It can be difficult," said teen librarian Holly Leftridge of creating a Rube Goldberg machine. "You create a goal, and then you set up steps to make that goal happen. That can be turning on a faucet, opening a door, turning on a light switch, pushing over a book or popping a balloon."

The machine designed by the students on Friday was made to catapult a small ball into a tower of cards, knocking it over.

It started with one of the students blowing a small ball out of a tube. That ball then hit a larger ball, which rolled down a ramp into a stack of books, knocking them over like dominoes, the last one engaging the catapult, which threw the ball into the tower of cards.

"I think this is a great thing to do with this age group because first off, it's fun, but it also teaches engineering concepts," Leftridge said.

The challenge was open to students in grades six through 12 and took approximately 90 minutes to complete.