What factors matter and how they are related
Once scientists begin explaining, they make guesses about what factors or aspects of the phenomenon are important and how they might be related to each other. These form the basis for tentative explanations that can be tested and refined. Engaging students in considering what factors might matter helps them develop partial explanations that they can test.
A closer look at uncertainty in the classroom
After students have been observing a decomposition chamber for a week, one observation many students seem interested in is that the cherry tomato does not seem to be getting moldy. Engaging in a discussion of this observation and asking students to propose and discuss possible explanations helps them to think about factors that might matter for decomposition.
Students propose and discuss possible explanations
Sam writes the question on the board, “Why is the cherry tomato not getting moldy (but the strawberry is)?” She tells students that their job is to share ideas – not to answer the question but to engage in “maybe...” thinking that can help the class develop more ideas and questions.
As students discuss their ideas, they draw on their experiences with decomposition outside, with food at home, and with the different materials in the classroom.
The board after the discussion, showing a record of students’ thinking
They pose questions, agree and disagree with each other. Ideas include:
“Maybe the skin protects it.”
“Maybe some materials mold faster than others.”
“Maybe there’s chemicals in some things that stop them from molding.”
“Where is the mold coming from?”
“Maybe it comes from the dirt.”
“But things on counters can get moldy.”
The discussion of the cherry tomato leads to the possibility that the skin could protect it, that the amount of moisture in a material matters, that the chemical makeup of the fruit matters, and a question about where the mold is coming from. These provide starting points for investigations that can help students make progress on big ideas related to identifying decomposers, decomposers’ life cycles (reproducing, traveling, eating), and decomposers’ needs.
Instructional moves to support this form of uncertainty
Provide sustained time and experience with the initial phenomenon.
Rather than moving right from noticings to questions, encourage students to develop tentative explanations (I think it might be because… X might matter for…).
Use pen-and-paper models of how and why phenomena might have occured to elicit and compare ideas.
Where else does this form of uncertainty come up?
Explore Related Cases
Other Ways to Learn More
Take a look at the first lessons of the Decomposition Investigation to see how they are designed to elicit students’ uncertainty about what factors matter and how they are related.
