Past a little cemetery on Appledore Island, six miles off the southern Maine coast, a group of 15 undergraduates and their two instructors paused at a low lichen-covered stone wall, their ears tuned to the shrubs.

"There's a catbird, giving that rusty hinge sound, hear it?" said Hal Weeks, assistant director of Shoals Marine Lab, an undergraduate teaching facility on Appledore Island that is administered by Cornell and the University of New Hampshire and hosts up to 180 students each summer. There, Weeks is teaching "Ecology of Animal Behavior," along with colleague Will Kimler, an associate professor of history at North Carolina State University.

That morning's bird walk was aimed at familiarizing the students with the 95-acre island and teaching them how to observe, ask the right questions and reason out answers.

The four-credit, June 30-July 14 course, one of 14 classes being taught at Shoals this summer, serves as an introduction to the scientific method where students propose hypotheses to scientific riddles and then design and carry out strategies for proving or disproving their theories.

"We want to teach critical thinking by showing students how to conduct a scientific investigation," Weeks said.

After the bird walk, the students spread out along the island's shoreline to measure the length of rockweed, a brown algae growing on the rocks. The students were tackling the question of whether they thought the rockweed would be longer low on the rocks, where it spends more time completely submerged as the tide rises, or higher up in their habitat range. In small teams, the students measured five plants for length and bushiness in each area. Later, the class would collate the data and determine whether the findings supported their theories for which area is more conducive to longer growth.

Along with lectures that focus on how ecology and evolution influence the behaviors of animals and plants found along the coastal marine environs of Appledore Island and elsewhere, the course includes numerous exercises for learning how to interpret behavioral patterns through data. For example, on the following day, the class went into the field, played recordings of territorial songs to sparrows, took notes on the birds' responses and then provided interpretations.

In the end, each student must complete a short-term, independent field study that they design. In prior classes, one student created a tank with various environments -- rocky, sandy, deep and shallow water -- to see which was preferred by the rock gunnel, a brown-speckled eel-like fish that inhabits the island's rocky intertidal zones; another student designed experiments to study how prey size determines the eating habits of orb-weaving porch spiders.

Overall, the instructors hope their course has a lasting impact on students, by exposing them to the process of reasoning and scientific thinking, skills they may use in all aspects of their lives.

"I like a student who comes here, and through hands-on learning, he or she may decide to become a scientist -- or not," Kimler said.