Hands-on Activity Make Your Own Temperature Scale

Learning Objectives

After this activity, students should be able to:

• Explain how a thermometer works.
• Describe the physical changes that occur in a thermometer with increasing or decreasing temperature.
• Explain how engineers use thermometers in everyday applications.
• Develop a scale for measuring temperature on a thermometer they build.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

Common Core State Standards - Math

International Technology and Engineering Educators Association - Technology

State Standards

Materials List

Each group needs:

• clear, narrow-necked plastic bottle (~355 ml [12 oz] water bottles work well); ask students to bring rinsed plastic bottles from home
• clear, plastic drinking straw
• Make Your Own Temperature Scale Worksheet, one per student

For the entire class to share:

• a few thermometers
• measuring cups
• 207 ml (7 oz) rubbing alcohol
• 207 ml (7 oz) water
• large glass jar (to mix the alcohol and water)
• stirring rod
• food coloring
• rulers
• fine-point permanent markers
• modeling clay

Worksheets and Attachments

Introduction/Motivation

When have you used a thermometer? Have you ever used one when you were sick or 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 an oven that only warms the food, but not enough to cook it? 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 stoves, 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.

Procedure

Background

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

• A week before the activity, ask each student bring to school a clear, plastic disposable bottle with a narrow neck.
• Gather materials and make copies of the Make Your Own Temperature Scale Worksheet.
• Prepare a mixture of equal parts rubbing alcohol and water. Each team needs about 59 ml (2 oz) of this mixture. Use a stirring rod to keep the solution mixed.

With the Students

1. Pour about 1/4 cup (~59 ml or 2 oz) of the alcohol-water mixture into each bottle. This should fill 1/8 to 1/4 of the bottle.
2. Add a few drops of food coloring to the mixture and swirl gently to mix.

3. Using a fine-point permanent marker, have the student teams use a ruler to make equally-spaced marks on the straw. They can use any division they want, as long as the marks divide the straw equally. Advise them to be careful not to bend the straw in this process.
4. Ask students to consider how the scale on a thermometer is marked. Then, have them carefully number the marks on their straw. Their numbers may be negative or positive.
5. Direct the teams to decide on a fun unit of measurement for their straw. For example, a commercial thermometer measures in degrees Celsius, Fahrenheit or Kelvin. Have students develop their own temperature scale names, perhaps degrees Cyndi or temperature measured in silly spots. Direct students to record their temperature scale information on their worksheets.
6. Place the straw in the bottle and hold it at the neck of the bottle without letting it touch the bottom.
7. Use modeling clay to seal the neck of the bottle so the straw stays in place. The finished thermometer should look similar to the Figure 1 diagram.

8. Have students wrap their hands around the bottle and observe what happens to the mixture in the bottle. Direct students to record on their worksheets the thermometer reading using the numbers on their scales. For more dramatic results, place the thermometer in a tub of warm water.
9. Have each team use a real thermometer to measure the temperature of their hands (or tub of water). Record this temperature on the worksheet next to the reading from their thermometers.
10. Have everyone place their thermometers in a location away from a source of heat (a hallway instead of in the classroom, or some distance away from a heater). After several minutes, have students record the air temperature reading using their new thermometers. The teacher provides a measurement using a commercial thermometer.
11. Move the thermometers to a source of heat (the warmer classroom instead of a hallway, or near a heater) and repeat.
12. Have students place their thermometers in secure places around the classroom and record the temperature throughout the day. At the same times, record the corresponding Fahrenheit or Celsius thermometer reading, and note the times the measurements were taken.
13. Have students complete their worksheets.
14. As a class, share, compare and discuss the results. Discussion prompts:

• Do you see any correlations in your data when the temperature is cold and the fluid in your thermometer drops, or how the fluid rises with the introduction of heat?
• Compare the scale on your thermometer to the scale on the real thermometer. How many units on your scale equal 1 unit on the real thermometer? Can you convert from one scale to the other? Can you convert from one team's scale to another team's scale?
• How might understanding the thermal properties of objects, including measuring their temperatures, be important in many everyday engineering applications?

15. Assign students to individualy write journal reflections or paragraphs about the activity.

Vocabulary/Definitions

absolute zero: The theoretical temperature at which substances possess no thermal energy; equal to -273.15°C, -459.67°F or 0°K.

conduction: The transmission or conveying of heat, sound or electricity through touching materials, without perceptible motion of the materials themselves.

conductor: A material through which energy (electrical, thermal or sound) can be easily transferred.

contract: To reduce in size by drawing together. The liquid inside a thermometer contracts when the temperature gets colder.

expand: To increase in size. The liquid inside a thermometer expands when the temperature gets warmer. Heat makes a liquid expand.

heat energy: A form of energy associated with the motion of atoms or molecules, and capable of being transmitted through solid and fluid media by conduction, through fluid media by convection, and through empty space by radiation.

heat transfer: The transfer of thermal energy between bodies due to a difference in their temperatures.

insulator: A material through which energy (electrical, thermal or sound) cannot be easily transferred.

temperature: The degree of hotness or coldness of a body or environment. A measurement of thermal energy. The average kinetic energy of the particles that make up an object.

thermal energy: The energy an object has due to the motion of its particles. Also called heat energy.

thermal equilibrium: When the temperatures of two or more bodies are equal.

thermometer: An instrument for measuring temperature, especially one having a graduated glass tube with a bulb containing a liquid (often mercury or colored alcohol) that expands and rises in the tube as the temperature increases.

thermometer scale: A system of ordered marks at fixed intervals used as a reference standard for temperature measurement, and based on the freezing and boiling temperatures of water. For example, Celsius, Farenheit and Kelvin thermometer scales, used by scientists and engineers for different applications.

Assessment

Pre-Activity Assessment

Question/Answer: Ask students the following questions and discuss as a class.

• What is thermal energy? (Answer: The energy of heat, or the energy an object has due to the motion of its particles.)
• What does a thermometer do? (Answer: It measure temperature.)
• Why might an engineer want to measure the temperature of an object? (Answer: To make sure the object is the right temperature, neither too hot nor too cold, for the item to function properly. Also, engineers design products that provide heat, such as an oven or hair dryer.)

Activity Embedded Assessment

Worksheet: Have students record their observations on the Make Your Own Temperature Scale Worksheet. Review their answers to gauge their mastery of the subject.

Post-Activity Assessment

Questions: Ask the students and discuss as a class:

• What happens to the liquid in your thermometer when it gets colder? (Answer: It contracts and the reading on the straw is lower.)
• What happens to the liquid in your thermometer when it gets warmer? (Answer: It expands and the reading on the straw is higher.)
• What could happen if the thermometer was placed in a very hot liquid? (Answer: The liquid might expand so much that it came out the top of the straw.)

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.)

Troubleshooting Tips

Warn students not to drink, or even taste, the rubbing alcohol, or the alcohol-water mixture.

Make sure a good seal exists between the straw and the bottle neck.

Activity Extensions

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

• While this activity is good practice for measuring and marking off units, for younger students it may be helpful to give them a specific unit to measure, such as centimeters, to make sure the straw is marked off in equal increments.
• For younger students, have them copy the example paragraph provided in the Journal Reflection post-activity assessment in the Assessment section. Write the paragraph on the board, leaving some blanks for students to fill in key words.
• To add a math component for upper grades, have students graph the change in classroom temperature throughout the day, using both thermometer readings.
• For advanced math students, have them complete the Temperature Conversion Worksheet.

References

Copyright

Contributors

Supporting Program

Acknowledgements

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.