"Labs were originally designed to help students learn about the nature of science and what it meant to do experiments, but more and more the labs gave students laundry lists of instructions and tasks to carry out, and they just did not require them to use their brains," Holmes said.
One of the other authors of this new study, physicist and Nobel laureate Carl Wieman at Stanford University, had previously analyzed every decision made and question asked by students doing a physics experiment. The team used this research to develop the new teaching strategy for critical thinking.
"At the core of our teaching strategy is the idea of making comparisons, making sense of the comparisons, and then making decisions about how to act on them," Holmes said.
The researchers tested their strategy with about 130 students in a calculus-based introductory college lab course in physics. As the students conducted simple physics experiments, they were given explicit instructions to repeatedly compare their data with other data they or others previously gathered, discuss their results and ideas with other groups, and act on these comparisons by modifying their experiments or models to improve the quality of their data or models -- for instance, to gather data less filled with uncertainty, or develop models that fit their data better.
The investigators found the students in this experimental group were 12 times more likely to propose or make changes to improve their data or methods than about 130 other students who had taken the course without this strategy in place the previous year. The students in the experimental group were also four times more likely to identify and explain a limitation of a model using their data.
"The sheer size of the effect was way bigger than we were expecting," Holmes said.
Intriguingly, these improvements persisted in a subsequent physics course taken the following year that the researchers were not involved in -- for instance, students in the experimental group were significantly more likely to analyze and defend any new ideas they proposed than their peers. "That was a huge surprise, but a very welcome one," Holmes said. This improvement made the researchers realize that the students were not just following this strategy because the researchers told them it was important -- "they thought it was important too," Holmes said. "That's a big deal."
The researchers suggested this approach could be applied to other domains such as teaching journalism. Instructors can have students write articles, compare their results with professional or peer versions of those reports, and then come up with ways to improve their own stories.
"One of the neat things about this work is that it teaches students to think about experiments in an iterative way — building models, testing models, getting measurements, comparing measurements, all so that students can do experiments better the next time," said physics education researcher Ben Zwickl at Rochester Institute of Technology in New York, who did not take part in this research. The researchers are part of the Northern Grapes Project, founded in 2011 and funded by the U.S. Department of Agriculture. Universities and labs in twelve states ranging from New York through New England and the upper Midwest are involved.
Three thousand new vineyards have been planted across the dozen states, said Anne Fennell, one of the researchers and a professor of plant sciences at South Dakota State University in Brookings. Many growers in the region began cultivating wine grapes as a hobby.
Fennell said there are 30 species of native grapes in North America, but none that produce drinkable wines. All the grapes that do, including the cabernets and pinot noirs of California, Oregon and Washington, were imported from Europe, beginning in the 18th century.
While places such as California’s Napa Valley and Oregon’s Willamette Valley have climates and soils in which lush wine grapes thrive, much of the U.S. has more extreme weather, with very cold winters and short growing seasons.
The pinot noir of Burgundy and the cabernet sauvignon of Bordeaux cannot survive in those extremes. Pinot noir takes about 135 days from first bud to harvest, according to Yves Tourre, adjunct senior research scientist at the Lamont-Doherty Earth Observatory in Palisades, N.Y., who studies the effect of climate on biological organisms.
Many places in North America cannot provide that many days of suitable conditions. Brookings, where Fennell works, has a growing season of 111 days.
The intensity of the sun is adequate, but the great European grapes wouldn’t be ready for harvest until October, she said. By that time, much of northern North America already has seen frost or worse.
Temperature extremes are another problem, Fennell said. If ice forms between the cells of the vine, the vine will die, another reason classical grapes can’t be planted in this region.
About 1,000 years ago in England, during the Middle Ages, there was a period of relatively warm weather that supported wine grapes. But as the climate changed and the weather got cooler, it no longer became possible to grow good wine grapes there. With the modern climate now warming, there are about 500 vineyards in England and Wales, and new ones starting regularly.
The American scientists are creating new complex hybrids by combining vitis vinifera -- the scientific name for the classic European-American wine grapes -- with the most common cold-resistant North American grape species, vitis riparia.
“It is a black grape, a very strong color but highly disease resistant,” she said. “We are specifically using it to produce cold tolerance.”
Other cold-resistant grapes also fail to impress. “Some will burn your tongue right out,” she said.