## Hot Time in the Classroom

### Michael HallDuval County Schools

#### Description

Students use a thermometer and ice to learn that temperature is a measure of the average translational kinetic energy.

#### Objectives

Describes, analyzes and generalizes relationships, patterns, and functions using words, symbols, variables, tables and graphs.

The student knows that temperature is a measure of the average translational kinetic energy of motion of the molecules in an object.

#### Materials

-Beaker for each group
-Thermometer for each group
-Hot plate or other heat source for each group
-Ice
-Graph paper
-Pencil or pen
-1 Ruler for each group
-Watch or other timing device for each group

#### Preparations

1. Have enough thermometers, beakers, and heat sources for the number of groups that will participate in the lesson.
2. Provide graph paper, timing device (watch), and ruler for each group (or student).
3. Bring enough ice for the number of groups that will run the experiment. Ice should stay in the freezer until needed. If a cooler is used, tell students to measure the temperature of the ice and start timing as soon as they place it in the beaker.
4. Prior to doing this with your students, run the experiment and collect data so that you can help students make their graphs (establish scales, etc.).

#### Procedures

1. Take a small brown paper bag and hold it fully opened over an alcohol burner (or other heat source) and allow it to rise. Ask students to describe what they saw.

2. Describe that hot air rises as the result of molecules moving quickly. This is caused as a result of kinetic energy being added by the flame (or heat source) to the air in and about the paper bag. Relate to the student that all materials act the same when they are heated.

3. Have students discuss ways to measure temperature and time.

4. Have students measure the temperature of several materials that are at different temperatures. Have students time several time intervals.

5. Have students place ice cubes in a beaker. Place the beaker over a heat source (the type of heat source will affect the time needed) like the one used to start the lesson. Have students record the temperature of the ice as it melts and continue to measure the temperature change until it begins to boil for a few minutes. Time intervals should be set according to the heat source that you are using. Have students graph the data. Have students discuss the reason for the two flat areas on the graph.

6. Check graph for the correct shape. Compare to the sample graph. (See Associated File) Please note that graph may be skewed depending on time interval chosen. Lead discussion of the graph to point out that the areas that are flat result in times where the material is absorbing energy to change phase and not increase temperature.

#### Assessments

As a formative assessment, teacher can compare the graph created by the students to the Temperature vs. Time Graph. (See Associated File) Directed discussion of the graph as it relates to translational kinetic energy will help students understand the concept of temperature as a way to measure it.