# Make a Thermometer to Study the Temperature

## Summary

3rd
Group Size
2-3 students
Active Time
100 minutes
Total Time
100 minutes
Area of Science
Weather & Atmosphere
Key Concepts
Temperature
Credits
Sabine De Brabandere, PhD, Science Buddies

## Overview

Students experience the weather every day: they feel cold spring mornings and warm summer afternoons. This hands-on lesson helps them quantify how hot or cold it is by using a thermometer they will make themselves! Based on their gathered data and observations, students can infer patterns about how temperature varies by location and time.

## Learning Objectives

• Define temperature
• Record temperature data with a homemade liquid thermometer
• Make graphs representing temperature data
• Interpret, compare, and explain temperature data
• Understands that outdoor air temperature changes over time and with place

## NGSS Alignment

This lesson helps students prepare for these Next Generation Science Standards Performance Expectations:
• 3-ESS2-1. Represent data in tables and graphical displays to describe typical weather conditions expected during a particular season.
• 3-ESS2-2. Obtain and combine information to describe climates in different regions of the world.
This lesson focuses on these aspects of NGSS Three Dimensional Learning:

 Science & Engineering Practices SEP 4 Analyzing and Interpreting Data. Represent data in tables and/or various graphical displays (bar graphs, pictographs and/or pie charts) to reveal patterns that indicate relationships. Analyze and interpret data to make sense of phenomena, using logical reasoning, mathematics, and/or computation. Compare and contrast data collected by different groups in order to discuss similarities and differences in their findings Disciplinary Core Ideas ESS2.D: Weather and Climate. Scientists record patterns of the weather across different times and areas so that they can make predictions about what kind of weather might happen next. Crosscutting Concepts Cause and Effect. Cause and effect relationships are routinely identified, tested, and used to explain change. Events that occur together with regularity might or might not be a cause and effect relationship.

## Materials

For each group of students:

• Clear plastic drinking straw, preferably 0.2 inches in diameter. See the technical note for advantages and disadvantages of straws of different diameters.
• Metric ruler
• Fine-tipped permanent marker
• Clean narrow-necked, small bottle with lid. Travel size bottles like these available from Amazon.com work well. Cleaned empty food coloring or vanilla extract bottles work well too.
• Rubbing alcohol, 70% works well.
• A few drops of red, blue, or green food coloring. Liquid food coloring works best.
• Paper or cloth towels
• Modeling clay. Air-dry clay works well. Ultra-light modeling clay is easy to model and clean.
• Medicine dropper or syringe
• Water
• Small bowl
• Ice cubes
Technical note:
When choosing the materials for the homemade thermometer, consider that narrower tubes (straws) result in a more accurate thermometer because the same expansion or contraction of liquid and air will cause a rise or fall over a longer distance. As a drawback, the narrow straw might decrease the maximum temperature that the thermometer can reach. It might also be harder for students to drop the liquid in the tube while making the thermometer. Science Buddies staff found that a 0.2 inch diameter straw works well.

For the class:

• A store-bought thermometer. Kitchen or outdoor thermometers work well.

## Background Information for Teachers

This section contains a quick review for teachers of the science and concepts covered in this lesson.

Temperature, a measure of warmth or coldness, is an important part of a weather report because we want to know how warm or cold it will be the next day or the following week. Scientists use the outdoor air temperature as one of many variables to specify weather. Monitoring temperature over a longer period of time and at different locations allows scientists to identify temperature changes and patterns. These patterns can then be used to predict future weather.

A device that measures temperature is called a thermometer. One type of thermometer is the liquid-filled thermometer. It consists of a liquid-filled reservoir at the end of a narrow tube. If the temperature of the liquid in the reservoir increases, it expands and rises into the narrow tube. When the liquid cools, it contracts, allowing the liquid in the tube to fall to a lower level. Therefore, high levels of liquid in the tube indicate a higher temperature, and low levels indicate a lower temperature. Figure 1 shows an example.

Figure 1. A store-bought liquid thermometer.

To compare temperature readings from different thermometers, a thermometer has to be calibrated. When calibrating a thermometer, a number value is assigned to a certain level of liquid in the narrow tube, and thus matched to a specific temperature (hotness or coolness). There are several different measurement units for temperature. Celsius and Fahrenheit are two commonly used temperatures scales. Both scales use the temperature at which water freezes and boils at sea level as reference points. The scale is then created by breaking the section in between these reference points down into equidistant intervals. As shown in Table 1, temperature scales can differ in the numbers chosen to represent these reference point temperatures.

Reference points Celsius Fahrenheit
temperature at which water freezes at sea level 32°
temperature at which water boils at sea level 100° 212°
Table 1. Reference points for the Celsius and Fahrenheit scales.

When it gets cold enough, the temperature readings can become negative for the Celsius scale, the Fahrenheit scale, and the scale used in the thermometer created in this lesson. Because thermometer readings change in discrete steps (for example, consecutive readings could indicate 2°C and 3°C, or 10°C and 25°C), students might get the impression that the temperature changes stepwise, in jumps. This can reinforce a common misconception that "cold" and "warm" are two different entities rather than extremes of a continuum. Arranging pictures on a continuum from very cold to hot might help to clear up this misconception.

In this lesson plan, students will build their own liquid thermometer and use it to monitor temperature changes over time and at different locations. They can then look for patterns in their measurements to understand more about their local weather.

Figure 2. A mark on the narrow tube indicates the temperature of ice water.

## Lesson Plan Variations

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