A tiny, single-celled organism is having a big effect on elementary, middle and high school science teachers across the country who use it as a teaching tool, thanks to Cornell's Advancing Secondary Science Education with Tetrahymena (ASSET) program.

Four workshops this summer trained teachers to use various teaching modules featuring the freshwater protozoa Tetrahymena thermophila in their classes. Modules covered such topics as cell structure and function, evolution, reproduction, genetics and taxonomy, and the role of science in society.

The program provides schools with kits to run lab experiments, including teacher and student protocols, organisms, petri plates and growth media, and basic microscopes and digital cameras for schools that cannot afford them.

"We want all schools to use our materials, but we especially want to reach out to rural schools and those with high minority populations that are traditionally underrepresented in science," said Donna Cassidy-Hanley, a senior research associate in the Department of Microbiology and Immunology and ASSET co-principal investigator. The program, funded by a $1.2 million Science Education Partnership Award from the National Institutes of Health, started in 2009.

One of the modules, for example, allows teachers to create microcosms to study evolution.

"Evolution is very difficult to teach in real time," but these nonpathogenic, rapidly reproducing organisms allow for simple experiments that take just seven to 10 days, Cassidy-Hanley said.

In the evolution module, students create a culture with Tetrahymena and soil bacteria they feed on in a simple sugar solution. In a week, two types of soil bacteria mutations proliferate; one appears in a film at the top of the water column, while another settles at the bottom. At the top, the bacterial mutations allow them to stick together, making them too large for filter-feeding Tetrahymena to ingest; the bacteria colonies at the bottom have adapted to thrive in low oxygen environments, which Tetrahymena avoid.

"You can see these different types of bacteria very clearly when you plate them out," said Cassidy-Hanley. Bacteria from each region of the liquid culture form colonies with very different shapes and sizes that can be easily viewed on agar plates, even without a microscope.

This year's summer workshops were:

Due to increasing interest, ASSET also tested a virtual workshop format this summer. Linked to an instructor at Cornell and using materials furnished by ASSET, several teachers participated in a mini-workshop at the University of Missouri. ASSET staff members hope to increase online and elementary teacher workshops, expand modules and the lending library, and apply for new grants as the current one ends in 2014.

ASSET activities are facilitated by the NIH-funded Tetrahymena Stock Center at Cornell, a national repository for Tetrahymena that is also widely used as a research model.