Heating & Cooling Investigation
In this second-grade investigation, students explore how heating and cooling different materials changes their properties, as they seek to understand how different ingredients make a cake. They support claims about whether heat changes the state of materials with evidence, and wonder about a few (chocolate chips, a rock). They explore the idea of reversible and irreversible changes, considering which materials can return to their original form after being heated or cooled and which ones cannot. They use this information to explain the phenomenon of a cake baking.
Context
This investigation is part of a unit on properties of matter, centering on the phenomenon of liquid cake batter turning into a solid cake when it is baked.
Authors: This investigation was developed with support from Griselda George, Lauren Woldemariam, and Diana Garity (Somerville Public Schools).
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NGSS Standards
2-PS1-1: Plan and conduct an investigation to describe and classify different kinds of materials by their observable properties
2-PS1-4: Construct an argument with evidence that some changes caused by heating or cooling can be reversed and some cannot.
Forms of Uncertainty
Among other uncertainties, students in these lessons are supported to engage with:
What to count as evidence: As children investigate how materials (ice, butter, chocolate chips, an egg) change when heated, they grapple with identifying the state of heated chocolate chips. Some of them think chocolate chips melted into a liquid while others are less convinced.
How to generalize: Students test a rock along with other materials they heat on a hot plate. It does not change into a liquid. They must decide whether they can claim that heat doesn’t change rocks’ state.
How to apply findings: Students use what they have learned about different materials heating to explain how the cake turned into a solid, a process that involves several ingredients combining and changing.
What counts as a satisfying explanation - At the end of their investigation work, students think that the liquid egg in the batter that changes to a solid helps explain how the batter turns into a cake, but there are other parts of the phenomenon they still haven’t explained, like the holes in the cake.
Explore the full Uncertainty Overview to learn more about these and the other forms of uncertainty that students engage with in this investigation.
What Happens in This Investigation?
Engaging with the Phenomenon
The classroom community works together to make a cake. Children explore different materials, describing their properties. They combine and stir ingredients, then describe (and eat!) the cake that the teacher bakes from the batter. They pose questions about why the cake puffs up, has holes, and turns into a crumbly solid. Over the next several lessons, they explore the properties of materials and read about liquids and solids.
Explore related forms of uncertainty, instructional materials, and tools.
What counts as a satisfying explanation
Heating & Cooling investigation overview
Planning and Conducting the Investigation
The teacher reminds children that they thought that heat was really important for making the cake and asks children how heat changes materials. After exploring how heat changes ice, children make predictions about how other materials will change when placed on a heating plate at about the temperature of the oven. The teacher heats materials in tins, then passes them to groups of students to observe. They record their observations, considering whether each material changes state when heated. Later, they observe the same materials when heat has been taken away, observing whether their properties have changed back.
Explore related forms of uncertainty, instructional materials, and tools.
Planning investigations conversation tool
Supporting Claims with Evidence
Children engage in discussion about how the materials changed when heated, supporting their claims with evidence and explanations of why they changed. They are sure about some (the butter, the egg) but less sure of whether the chocolate chips changed to a liquid and whether rocks could change with heat, even though they didn't. They discuss the idea that different materials may change with different temperatures. They also make claims about whether materials changed back when heat was removed, beginning to think about whether some of the properties that did not change back (e.g. the shape of butter) could be changed back (for example, by cooling the butter in a mold). But some properties – like the form of the egg or the separation of the butter into different materials – seem harder to change back.
Explore related forms of uncertainty, instructional materials, and tools.
Developing Explanations
After conducting the investigation, children work in groups to present what they have learned about one material, and how that helps explain the cake baking. Children have made progress on explaining the cake, but they have a lot of remaining questions. The teacher uses various resources, including videos of lava and volcanos, and a book, A Delicious Experiment, to build on children's sensemaking and provide information that helps them develop a satisfying explanation.
Explore related forms of uncertainty, instructional materials, and tools.