What do you get when you combine eighth-graders, batteries, wheels, small motors and a lot of creativity?

At Doherty Middle School, that combination yields radio-controlled robots.

For nine weeks eighth-graders have engineering classes, where they are taught the mechanics of building a working robot, but also problem-solving, ingenuity and patience, said teacher Steve Cogger.

Last week, two professional engineers from iRobot, the Bedford-based company that makes Roomba vacuums, visited Cogger's classroom to talk about engineering and see the eighth-grader's robots in action. Wheels and motors for the robot project were donated by iRobot.

Motors whirred as teens drove one-of-a-kind robots around the classroom floor. One robot with a hammering arm knocked down pieces of wood as another tossed a ball with a catapult.

"There is a lot of creativity," said eighth-grader Dylan King, looking around the classroom. "What people thought they could do is actually happening. That's cool to see."

Dylan and his classmate Jonathan Tetreault designed and built a robot that lowered a wooden drawbridge and then drove over it. The design process was not without its frustrations, they agreed, but they learned to focus on priorities and persevere.

"We tried to think of the most out-of-the box design, something we thought someone could actually use," said Dylan.

"We didn't think you could really lay out a bridge with a robot. But we're eating our words now," said Jonathan.

For the project, Cogger breaks his class into teams of two, and gives each team a motor and two wheels. The assignment is to build a robot that can be driven via remote-control and does some other type of task.

From there, the sky's the limit. Teams have built robots that shovel, lift or push things. One team installed an electromagnet on their robot, built from instructions they found online, said Cogger. Another installed a digital camera that shot photos as the robot drove.

After a few weeks, once students have designed a chassis and attached the motor, Cogger has them drive their robots through a slalom course. Robots that have problems maneuvering the course are tweaked or rebuilt before extra design elements are added.

"It's good to see students come up with an idea, and stick with it until it works. It's meaningful because it's their idea," said Cogger.

Several Doherty eighth-graders will demonstrate their robots during a School Committee meeting, said Cogger.

Sixth-, seventh- and eighth-graders at all three of Andover's middle schools have engineering lab for a trimester as part of their integrated arts rotation.

Partially funded by grants and donations, Andover's engineering labs teach concepts tested on the eighth-grade science MCAS test. Andover middle-schoolers take engineering in addition to other science classes.

Each eighth-grader at Doherty Middle gets a chance to build a robot in engineering classes. At West Middle School, eighth-graders build radio-controlled airplanes. Wood Hill Middle School's engineering program is in its second year, so airplanes, robots or another building project will be added to curriculum in the future.

Cogger formed a relationship with iRobot through a Cornell University alumni event, introducing himself to the company's chief engineer, a fellow Cornell alum.

From there, Cogger and Assistant Superintendent Susan Nicholson visited iRobot's STEM (science, technology, engineering and math) outreach initiative. Using Roomba parts he'd bought online, Cogger had built a prototype robot to show the company what he'd have students doing. iRobot agreed to donate parts for the project, and sends engineers every nine weeks to speak to students about the field of engineering.

Last week, Andrea Okerholm and Kristen Stubbs visited Doherty Middle eighth-graders, speaking about what it's like to work at iRobot and how they became interested in engineering.

They showed video clips of robots that climb stairs, drive through water, climb hills, over rocks and even through snow and ice. One video showed a remote-controlled robot used by the military, sent in ahead of soldiers, which shot video of a unsecured area and checked for bombs.