Heating & Cooling Investigation
In this second-grade investigation, students explore how heating and cooling 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 materials (chocolate chips, a rock). They explore the idea of reversible and irreversible changes, considering how the properties of some materials can change back when heat is removed (liquid water can change back to solid water in a freezer) but some can't (a solid egg does not become liquid again when left out overnight).
Context
This investigation is part of a unit on properties of matter. Students explore the how the ingredients of a cake become a liquid batter and then a solid cake. Throughout the unit, they explore ways of describing matter, mix matter, and consider pieces of matter so small they can't see them. They then consider how heating changed the batter and conduct an investigation into heating and cooling.
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 change when heated, they grapple with identifying the state of heated chocolate chips and argue about what to use as evidence: that the material doesn’t change its shape unless it is stirred or that it pours (very slowly).
How to generalize: Students test a rock or piece of metal 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 the state of the material.
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. They describe the properties of the ingredients. 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, reading about liquids and solids, and realizing it is not always easy to tell if something is a liquid or solid.
Explore related forms of uncertainty, instructional materials, and tools.
Heating & Cooling investigation overview
Lesson 1 from the matter unit: Developing initial explanations
Lesson 5 from the matter unit: Sorting matter into liquids and solids
Planning and Conducting the Investigation
In the middle of the unit, the teacher reminds children that they thought that heat was really important for making the cake. 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
Lesson 9 from the matter unit: Solid and liquid water
Lesson 11 from the matter unit: How does heat change materials?
Lesson 12 from the matter unit: Cooking the egg
Supporting Claims with Evidence
Children discuss 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.
Claims and evidence conversation tool
Lesson 13 from the matter unit: What happens when we remove heat?
Lesson 14 from the matter unit: What have we learned about our materials?
Developing Explanations
Children work in groups to consider 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 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.
What counts as a satisfying explanation
Constructing explanations tool
Lesson 15 from the matter unit: What have we learned about heating and cooling?
Lesson 16 from the matter unit: How can we explain the cake now?