Brianna: “The water can’t hold up stones like it holds up boats, so I know the stones will sink.”


Sr. Hennessey: “You sound so sure, let me try another object.”


Brianna: “No, you have to throw it in, you have to test my idea first.”


[Sr. Hennessey places a small stone in the tank; it sinks.]


Brianna: “See, I told you it would sink.”


[Sr. Hennessey puts aside a larger stone and picks up another object.]


Brianna: “No, you have to test the big one, too, because if the little one sunk, the big one’s going to sink, too.”


[Sr. Hennessey places the larger stone in the tank and it floats.]


Brianna: “No! No!” [Brianna shakes her head.] “That doesn‘t go with my mind. That just doesn’t go with my mind.”

During the activity described above, Brianna is involved in a form of introspection in which she is processing and interpreting both past and present experience. For example, when Brianna says, “I think both stones will sink…. I’ve seen lots of stones sink, and every time I throw a stone in the water … it always sinks,” she reveals her current thinking about how that particular stone will behave in the water, based on her past experience with how stones have behaved in water.

As the discussion continues, Brianna reveals her beliefs about the nature of water. She uses her beliefs about water to support her current beliefs about stones. For example, she says, “The water can’t hold up stones like it holds up boats. I know the stones will sink.”

Brianna also insists on two separate occasions that Sr. Hennessey test her prediction by saying, “You have to test my ideas first,” and “You have to test the big one, too, because if the little one sunk, the big one’s going to sink, too.” It is important to note that Brianna asks her teacher to test her prediction as opposed to asking her merely to test what happens with the stone; Brianna is consciously aware that understanding her own thinking is the object of the demonstration.

Brianna’s reaction to having the larger stone float indicates that she is aware that the outcome is anomalous, and that this anomaly is inconsistent with her current view of both water and stones. “No! No!” she says. “That doesn’t go with my mind.” Her comment also shows that she is thinking about her own scientific thinking; she is being metacognitive.

The level of thinking about scientific thinking grows more sophisticated over time. Here’s another scenario involving Sr. Hennessey and one of her sixth-grade students.

Jill wrote an essay as part of the assessment process in her physics class. Her assigned task was to focus on “the element of change” in her thinking. The following questions were posed:

  • Do you think your ideas about force or forces acting on various objects have changed?

  • If so, in what way have your ideas changed? Why do you think your ideas have changed?

Here’s what Jill wrote:



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