Snapshot: Investigating Heat Transfer
Ms. T’s goals: Students will understand heat transfer by conduction, particularly that heat is transferred from objects of higher temperature to objects or substances of lower temperature; thermal conductivity is a characteristic property of materials - some materials conduct heat more rapidly than others.
Snapshot: Students in Ms. T’s 5th period science class have been studying heat transfer. She begins today’s class by asking students to write the date and investigation question, Is thermal conductivity a characteristic property of a material? in their notebooks. Each pair of students has a cup and a plastic, a metal, and a wooden spoon on their table. Ms. T continues: In a few minutes you will fill your mug with ice cubes and water. Before you do, imagine you put your three spoons into the container of ice water and let them sit there for 4-5 minutes. Now you feel the part of each spoon that sticks up out of the ice water. What do you predict they will feel like once you’ve let them sit in a cup of ice water? When you write your prediction in your notebook, be sure to explain your reasoning.
When Ms. T observes that most students have finished writing, she asks students to share their predictions and reasoning with each other in table groups. She asks for a volunteer from each table to summarize some of the group’s ideas. Ms. T listens for students to talk about heat being transferred from the warmer spoons to the colder ice water so that after a while the handles of the spoons will feel colder. She also listens for ideas about whether the spoons will all feel colder or if one material will feel colder than another. She sums up what she hears: There seems to be some agreement that you predict that the spoon handles will feel colder because heat will be transferred from the warmer spoons to the colder ice water. There is less agreement on how the spoons will feel when you compare them to each other. It’s time to find out. I’m coming around with ice water so you can test your predictions.
After students have recorded their observations in their notebooks, Ms. T puts a chart on the board and each pair records their observations.
How did the spoons feel after being in ice water for about 5 minutes?
Material the spoon is made of:
Cooler than Room Temperature
About the same as room temperature
Ms. T writes this question on the board:
Looking at the class data, how would you explain why, after being treated exactly the same way, metal spoons felt colder than wood or plastic?
She asks students to take a few minutes to discuss their ideas in their table groups and then answer the question individually in their science notebooks. When she reads through her students’ explanations tonight, she plans to see if they include thermal conductivity as a characteristic property of materials. She thinks about what she might do tomorrow if a significant number of students do not make this point.