Connections, consequences, and understanding
HGSE Professor Tina Grotzer
Students in science classrooms commonly offer explanations that are based upon directly observable linear patterns. However, Tina Grotzer – HGSE assistant professor and principal investigator at Harvard Project Zero – suggests that scientific thinking requires students to go beyond linear patterns, and to make more complex assumptions about cause and effect. Grotzer has developed a curriculum called the Understandings of Consequence Project that encourages both teachers and students to approach science from a broader perspective.
People tend to look for simple linear patterns to explain the world around us. As infants, we perform acts that lead to direct and observable consequences: we cry and so we get picked up; we push the ball and it rolls away from us. These patterns are reinforced in early science education when teachers and students compile lists of things that float and things that sink. As we grow from childhood to adulthood, we continue to seek out efficient and easily observable patterns.
However, according to HGSE assistant professor Tina Grotzer, linear patterns don’t always work – and our tendency to explain the world in this way can impede science learning. “Most of the time linear patterns work: you want to turn on a light, so you flip the switch and it turns on,” Grotzer explained in a recent interview with Usable Knowledge. However, Grotzer argues, the consequences of our actions do not always follow a directly observable pathway. Pollution, for example: “If you dump oil or garbage down the drain in Cambridge, you have no way of knowing that it is actually affecting the water in Boston harbor. You don’t make the connection because you can’t see the outcome. There are lots of times when a simple model doesn’t work even though it’s efficient and quick.”
Assumptions that impede learning
In a $1.4 million grant from the National Science Foundation entitled “Learning to RECAST Students’ Causal Assumptions in Science through Interactive, Multimedia Professional Development Tools,” Grotzer is taking a closer look at the ways in which students understand causality. She has developed a science curriculum challenging students’ a priori notions of cause and effect.
In the first phase of the study, Grotzer and her team visited science classrooms, grades 3 through 11, to observe and interview students. What they found was that students tended to make a series of assumptions when searching for scientific explanations. These explanations largely assumed that causality is constructed from obvious and perceptible agents, and that a cause is close in time and space to its effects. Furthermore, the students did not take into account the indirect consequences of actions.
For example, when studying the food web, students tend to assume that green plants matter only to the animals that eat them, and not to the animals that prey on the green plant-eating animals. Actually, the contrary is true: if green plants were to disappear, the population of green plant-eating animals would diminish, leading to scarcity of food for the animals that eat them, and so on throughout the food web.
Developing a broader understanding
In response, Grotzer developed a curriculum, part of which is already in use in the Cambridge Public Schools, to help students question and restructure their notion of causality. Activities are designed to help students question their assumptions and to reveal the underlying causal structure.
In a segment on density, for example, the teacher takes two jars of liquid, one filled with water and the other with isopropyl alcohol. A large piece of candle is dropped into the isopropyl alcohol and a smaller piece in the water. The large piece sinks and the smaller piece floats.
When the teacher asks for an explanation, students tend to say that the larger candle sinks because it’s heavier. When the teacher switches the pieces of candle, the larger piece floats in the denser water, and the smaller piece sinks to the bottom in the less dense isopropyl alcohol – as the larger one did. “When I shift the candles, the kids’ eyes always get so big,” says Grotzer. “It totally shifts their mindset.”
Global warming is an example of a nonlinear chain of events that both adults and school children struggle to understand, according to Grotzer. “When we were kids,” she explained, “people used to throw their garbage out of the car window. You could see it accumulating along the roadside. When there was a campaign to stop people throwing their garbage out of the window, you could see the difference. With global warming, the greenhouse gases are not obvious: you don’t see them, you don’t know they are there, and so you don’t necessarily know that you are contributing.”
Understanding global warming is further complicated, according to Grotzer, by the fact that it’s both spatially and temporally removed. “It’s very hard to pay attention to something when the effect has a time delay,” says Grotzer. “It diffuses responsibility. The effects are also spatially removed so it’s hard to connect our own actions to public health issues happening on the other side of the world, such as the rise of certain kinds of mosquitoes. We are used to agent-oriented causality. We act and make something happen. I f you can’t connect your action to an outcome, then it’s easy to lose the sense of urgency about it.”
In the current phase of her project, Grotzer is working with the Harvard Smithsonian Center for Astrophysics to develop a professional development Web site for teachers. The site aims to help teachers develop the skills necessary to use the Understandings of Consequence curriculum, and also to develop curriculum ideas of their own. While Grotzer hopes the new site will be up and running soon, educators who wish to get a head start on this new approach to science education can access the entire curriculum at the Understandings of Consequence Teacher Resource Website at http://www.pz.harvard.edu/ucp.