Physical Science - 63 - Session 7
Session 7
Heat and Temperature
What makes the liquid in a thermometer rise or fall in response to temperature? Which contains more heat—a
boiling teakettle or a swimming pool of lukewarm water? In this session, we focus on the difference between heat
and temperature and examine how both are defined in terms of particles. We also use the particle model to
explain a number of everyday phenomena, from why things expand when they are heated to the role that tem-
perature plays in changes of state.
The Video
This session opens by examining the everyday but amazing phenomenon of ice and why it feels colder to us than
ice water. We then go to the Science Studio where we ask a fifth grader Joana what a thermometer will read after
it has been “bundled up” in a blanket for half an hour. Another fifth grader Lydia thinks out loud about whether or
not heat is matter.
Science historian Al Martinez takes us to the Saugus Iron Works in Massachusetts and recounts some of the his-
tory of the scientific understanding of heat through the processes of combustion and friction. We then take a
closer look at heat transfer between different forms of matter on a particle level.
Back in the Science Studio, Lydia compares how different wood and aluminum blocks feel to the touch. But what
is she measuring—heat or temperature? Then Joana takes the temperature of ice water just after the ice is
removed and later on, discovers that not all liquids have the same boiling point.
Continuing in the Science Studio, third grader Sara observes a classic demonstration of the effect of heat on the
volume of a solid. But what about liquids? At the Roosevelt School in Worcester, Massachusetts, science coordi-
nator Paula Proctor and teacher Gina Robertson lead sixth graders through an investigation of the effect of heat
and cold on the volume of a red liquid in a thermometer. If the liquid goes up, is its mass changing? The same
experiment is then repeated in the Science Studio, where Lydia weighs the thermometer liquid before and after
heating, and David, a fifth grader, conducts an experiment to determine the effect of heat on the density of air.
The session ends with a “bang” when lead forecaster Bill Babcock of the U.S.Weather Service explains how thun-
derstorms get started when warm, less-dense air next to the ground rises, taking water vapor with it.
Learning Goals
During this session, you will have an opportunity to build understandings of the following concepts:
• Heat is the transfer of energy between two objects with different temperatures.
• Temperature is a measure of the average energy of motion of particles.
• Heat is added when solids change state into liquids and when liquids change state into gases (e.g., in
melting, evaporation, and boiling).
• Heat is removed when gases change state into liquids and when liquids change state into solids (e.g., in
condensation and freezing).
