What to count as evidence
Scientists experience uncertainty about what to pay attention to as investigations start to deliver “results.” They have to figure out, and often spend considerable time debating, what forms of evidence are important and not important. Engaging students with uncertainty in evidence supports a need for argumentation- because students have grounds for disagreement. It can also help them them deepen their understanding of the phenomenon as they consider what is most important about it (e.g., is shriveling evidence of decomposition? Is it more important if plants stay green or grow seedpods?)
A closer look at uncertainty in the classroom
As second graders investigate how materials (ice, butter, chocolate chips, an egg) change when heated, they grapple with identifying the physical state of heated chocolate chips. Some of them think chocolate chips melted into a liquid while others appear less convinced. Navigating ambiguity in evidence supports children to engage in argumentation where:
Children draw on different properties of solids and liquids
Children offer other forms of evidence
Children draw on different properties of solids and liquids
As children discuss, they use the properties of liquids and solids on their chart, finding limitations in each.
“I think it was bit more of a solid because on our properties of solids chart, it says “keep, keep their shape unless you do something to them” and they did keep their shape until we touched them."
"It melted but it didn’t wanna lose its shape."
"So, I would say it was like a solid, both ways because it’s not spilling, but it is moveable."
"It didn’t move. Liquids move back and forth. This shape stayed. There was still a mark from where we dipped the popsicle stick."
"I agree (it is a liquid) because even if you have to mix it doesn’t mean it wasn’t a liquid… They pour."
Heated chocolate chips
Properties of solids and liquid chart
Children offer other forms of evidence
They begin to develop new forms of evidence as well, drawing on experiences at home and considering what it means for liquids to have no shape and pour.
"Like the chocolate chips you could count, but when they’re like together, all like one, you can’t really tell."
"When we put the thing in to stir it, it could go through the chocolate chips. It was sticking to it, but it could go into it which it could not do before they melted."
" I saw some stuff dripping down it. It was like sweating but in chocolate form."
"One time my dad wanted to make like .. melt chocolate in this little pot, on.. it took a couple minutes… it got really hot and then melted into a liquid. I knew it was a liquid because it was able to pour and it kept changing its shape. It had no shape. We poured it into a couple of containers and then we dumped it into the cake batter."
Children explore heated chocolate chips.
Instructional moves to support this form of uncertainty
Before investigations, consider what children might pay attention to as evidence and when they could develop different claims based on attending to different things.
Ask children, "What could we pay attention to to tell whether [answer to investigation question].
Provide resources such as child-generated charts of possible evidence.
Support extended and multi-sensory engagement with investigation materials to generate multiple forms of evidence.
Invite multiple responses to the question, allowing children to make claims, add evidence, and disagree.
Highlight when children's evidence differs, "so it sounds like you're paying attention to..., but you are using something else as evidence."
Where else does this form of uncertainty come up?
Explore Related Cases
Other Ways to Learn More
Consider Lessons 3, 5, and 6 of the Decomposition Investigation. How do you see students being supported to think about what to consider as evidence, while allowing them to grapple, disagree, and refine ideas over time?
