Hands-on Activity: Make Your Own Temperature Scale
Educational Standards :
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
Each group needs:
For the entire class to share:
Introduction/Motivation (Return to Contents)
When have you used a thermometer? Have you ever used one when you were sick or maybe to see what the weather was like outside? What are we looking for when we use a thermometer? (Answer: Temperature) Yes, temperature is what is measured on a thermometer. Temperature is actually a measurement of thermal energy. When we read a thermometer, we are reading a measure of how much thermal energy an object has. Microscopically, this thermal energy comes from a whole bunch of tiny little molecules bouncing around and running into each other in an object.
Who remembers what a conductor or an insulator is? A conductor of thermal energy allows heat to pass through its material, so the temperature of the object gets really hot. Materials that are good conductors of heat feel hotter to the touch than materials than are insulators, even if they are at the same temperature!
What happens when the temperature goes up in a thermometer? The liquid inside the glass tube rises. It rises because heat makes the liquid expand. When something expands, it means that it gets bigger. The opposite word for expand is to contract, or when something gets smaller. The liquid inside the thermometer contracts when the temperature gets cold. Can you think of another example when temperature makes something expand or contract? Try this at home: Blow up a balloon or a plastic bag and tie it off. Then place it in the freezer for a few minutes. What happens to the balloon or bag? (Answer: It shrinks.) What happens when you pull it out of the freezer into the warm air again? (Answer: It expands.) Different objects expand and contract at different rates. Liquids and gases expand and contract much more dramatically than solid objects, like metals or glass.
Thermometers measure temperature based on the expansion or contraction of a liquid — either red-dyed alcohol or mercury. Even though the liquid and the glass tube are at the same temperature, the liquid expands much more than the glass tube. When a thermometer touches another object, heat is transferred from the warmer object to the cooler object until their temperatures are equal. Heat transfer between touching objects is called conduction. Thermal energy always transfers from warmer bodies to cooler bodies until they are at the same temperature. If the thermometer gains thermal energy from its surroundings, the liquid in the thermometer expands. The liquid contracts if the thermometer loses thermal energy to its surroundings.
A thermometer scale is based on the freezing and boiling temperatures of water. In the Celsius scale, water freezes at 0 degrees and boils at 100 degrees. In the Fahrenheit scale, water freezes at 32 degrees and boils at 212 degrees. Degrees in the Celsius scale are larger than in the Fahrenheit scale. Scientists use the Kelvin scale, in which the lowest possible temperature is 0 Kelvin (about -273.15°C or -459.67°F), or absolute zero. Kelvin degrees are the same distance apart as Celsius degrees. Engineers use all three scales, but for different applications.
Why do you think engineers use a thermometer? Engineers need to measure the hotness or coldness of so many things they design. How would you like a refrigerator that does not keep your food cold? Yuck! Or a CD player that is so hot it melts your CDs? Engineers use thermometers to measure the thermal energy of an object that is being used by people. They must understand how much heat is being given off by a bedroom lamp or a fan. What good is a fan to cool your room if it is also heating all of the air that passes through it? Engineers also design appliances and equipment that use thermal energy to work, like ovens, heating systems and medical equipment. Engineers really need to understand how a thermometer works and how much thermal energy is being used in so many ways! Today, you are going to build your own thermometer and practice engineering by measuring the thermal energy of different conditions.
Vocabulary/Definitions (Return to Contents)
Procedure (Return to Contents)
Use the conversion equations below to convert temperatures in one scale to another.
To convert from Celsius to Fahrenheit:
To convert from Fahrenheit to Celsius:
To convert from Celsius to Kelvin:
Before the Activity
With the Students
- Can the students see a correlation when the temperature is cold and the fluid in their thermometer drops, or how the fluid rises when with the introduction of heat?
- Have students compare the scale on their thermometer to the scale on the real thermometer. How many units on their scale equal one unit on the real thermometer? Can they convert from one scale to the other? Can they convert from one team's scale to another team's scale?
- Explain that understanding the thermal properties of an object, including measuring the object's temperature, is important in many everyday engineering applications.
Attachments (Return to Contents)
Troubleshooting Tips (Return to Contents)
Warn the students not to drink, or even taste, the rubbing alcohol, or the alcohol-water mixture.
Make sure there is a good seal between the straw and the neck of the bottle.
Assessment (Return to Contents)
Question/Answer: Ask students the following questions and discuss as a class.
Activity Embedded Assessment
Worksheet: Have the students record their observations on the Make Your Own Temperature Scale Worksheet. Review their answers to gauge their mastery of the subject.
Questions: Ask the students and discuss as a class:
Journal Reflection: Ask the students to write a paragraph, in their science journal or on a sheet of paper, to explain what happened when they placed their thermometer in different conditions. Have them use the following vocabulary words in their paragraph: temperature, thermometer, thermal energy, engineer. Ask them to explain their thermometer's units of measure, as well. (Example paragraph: Today we made a thermometer. We measured the temperature around the classroom. It was warmer near the heater. Our units of measure are silly spots. Ten silly spots are close to one degree in Celsius. Temperature is how we measure thermal energy. Engineers use temperature to design products, like a toaster.)
Activity Extensions (Return to Contents)
Take the thermometers outside to a windy spot or in the classroom in front of a fan. How does the air movement (like wind) affect the thermometers (temperatures)?
Find the freezing temperature of water using each team's thermometer. Make an ice bath in a bucket and place each thermometer in the bath for a few minutes. Compare the temperatures for the different scales.
Have student teams prepare class presentations on different aspects of the history of the development of the thermometer, including important people: Thermoscopes, Santorio Santorio, Galileo Galilei, Daniel Gabriel Fahrenheit, Anders Celsius, Lord William Thomson Kelvin.
Activity Scaling (Return to Contents)
References (Return to Contents)
Dictionary.com. Lexico Publishing Group, LLC. Accessed October 5, 2005. (Source of some vocabulary definitions, with some adaptation) http://www.dictionary.com
Make a Thermometer: Watch How a Simple Thermometer Works. 2003. Science Projects, Energy Quest, California Energy Commission. Accessed October 3, 2005. (Source of activity) http://www.energyquest.ca.gov/projects/thermometer.html
ContributorsSabre Duren, Jeff Lyng, Malinda Schaefer Zarske, Denise Carlson
Copyright© 2005 by Regents of the University of Colorado.
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Acknowledgements (Return to Contents)
The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.