Sometimes everyday objects make the best teaching tools in the classroom.

Diane O'Dowd remembers sweating the first time she brought the giant cell to class.

She worried that her introductory biology students would sneer at her demonstration, thinking it condescending and grade-schoolish. But when she walked across the larger-than-life cell drawing, acting the part of a motor protein traversing the cell, eyes lit up across the room as the students grasped the concept.

A professor at the University of California, Irvine, O'Dowd doesn't sweat over her presentations anymore. Her “garage demos”—so called because that's where she forages for many of her materials—earn rave reviews. She might arrive at class toting tennis balls that stand in for hydrogen ions, or her daughter's old Halloween wig that doubles as a vesicle studded with spiky purple proteins. In a hurry one day, she grabbed a pair of old soccer socks to represent sister chromatids.

O'Dowd, who's been teaching for two decades, revamped her lectures five years ago as her son and daughter approached college age. “Would they like the class I'd been teaching?” she wondered. “I concluded that they would not be excited by listening to me lecture, uninterrupted, for 50 minutes.” To learn about incorporating active learning in large classrooms, she attended the HHMI-sponsored National Academies Summer Institute on Undergraduate Education in Biology. Now, with support as an HHMI professor, she is developing and testing educational techniques and teacher-training programs. Among those efforts are her famous demos, which are hits not only in the classroom but also on YouTube.

When O'Dowd thinks back to her own college years at Stanford University, a few courses stand out in her mind. One is introductory physics, where lecturers routinely use demonstrations, such as the professor who lies on a bed of nails to show that the force, distributed across so many points, doesn't break the skin. So O'Dowd rummaged through her garage and started to build: proteins from pipe insulation and membrane phospholipids from PVC pipes, Styrofoam, and an old hanger. She recruited her children as beta-testers for new demos before unveiling them in class.

She explains class content with old-fashioned PowerPoint slides and uses the demos to reiterate important concepts.

“It puts an exclamation point on the sentence,” says Michael Leon, Irvine's associate dean of undergraduate biology education.

O'Dowd found that students can misunderstand key concepts when they're presented two-dimensionally. For example, many students perceive DNA plasmids as a flat circle, which is how they're typically drawn. But they are actually loops, with empty space in the middle. Her 3-D “plasmid,” manufactured from an old garden hose, shows students the proper shape.

Illustration: Andrew Rae

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