Using Thermometers
Learn
Is it hot or cold outside? How can we tell exactly how warm or cool something is? We use a special tool called a thermometer!
What is a Thermometer?
A thermometer is a tool that measures temperature. Temperature tells us how hot or cold something is. We use thermometers to check the weather, see if we have a fever, or know when food is cooked.
What is Temperature?
Temperature is a measurement of how hot or cold something is. We measure temperature in degrees. In the United States, we often use degrees Fahrenheit (written as °F).
How to Read a Thermometer
- Look at the thermometer carefully.
- Find where the red liquid (or the arrow on a digital thermometer) stops.
- Read the number next to that point.
- That number is the temperature!
Important Temperatures to Know
- 32°F - Water freezes and turns to ice
- 70°F - A comfortable room temperature
- 98.6°F - Normal body temperature for a healthy person
- 100°F - A hot summer day
- 212°F - Water boils
Types of Thermometers
- Weather thermometer: Measures the temperature outside
- Body thermometer: Measures if you have a fever
- Cooking thermometer: Checks if food is cooked safely
- Digital thermometer: Shows the temperature as a number on a screen
Examples
Let's practice reading temperatures!
Example 1: A Cold Winter Day
The thermometer shows: 28°F
What does this mean? It is very cold! This is below freezing (32°F), so any water outside would turn to ice. You should wear a warm coat, hat, and gloves.
Example 2: A Nice Spring Day
The thermometer shows: 65°F
What does this mean? It is a pleasant temperature. You might wear a light jacket or long sleeves. Great weather for playing outside!
Example 3: A Hot Summer Day
The thermometer shows: 95°F
What does this mean? It is very hot! You should drink lots of water, wear sunscreen, and try to stay in the shade. Shorts and a t-shirt would be comfortable.
Example 4: Checking for a Fever
Normal body temperature: 98.6°F
The thermometer shows: 101°F
What does this mean? This person has a fever! A temperature over 100°F means the body is fighting off germs. They should rest and drink fluids.
Example 5: Comparing Temperatures
Monday's temperature: 55°F
Tuesday's temperature: 72°F
Which day was warmer? Tuesday was warmer because 72 is greater than 55.
How much warmer? 72 - 55 = 17 degrees warmer!
Practice
Answer these questions about thermometers and temperature.
1. What tool do we use to measure temperature?
Show Answer
A thermometer.
2. At what temperature does water freeze?
Show Answer
32°F. Below this temperature, water turns to ice.
3. The thermometer outside shows 40°F. Is it warmer or colder than the freezing point of water?
Show Answer
Warmer. 40°F is above 32°F (the freezing point), so water would not freeze.
4. Which is hotter: 85°F or 58°F?
Show Answer
85°F is hotter because 85 is greater than 58.
5. The temperature in the morning was 60°F. In the afternoon, it was 78°F. How many degrees did it warm up?
Show Answer
78 - 60 = 18 degrees.
6. What is normal body temperature?
Show Answer
98.6°F.
7. A child's temperature is 102°F. Do they have a fever?
Show Answer
Yes. A temperature over 100°F means they have a fever.
8. It is 25°F outside. Would you expect to see snow or rain?
Show Answer
Snow. 25°F is below freezing (32°F), so precipitation would fall as snow, not rain.
9. Yesterday it was 82°F. Today it is 75°F. How many degrees colder is it today?
Show Answer
82 - 75 = 7 degrees colder.
10. Put these temperatures in order from coldest to warmest: 50°F, 32°F, 75°F, 20°F
Show Answer
20°F, 32°F, 50°F, 75°F (from coldest to warmest).
Check Your Understanding
Question 1: Why do we use thermometers?
Show Answer
We use thermometers to measure temperature - to find out exactly how hot or cold something is.
Question 2: What are two important temperatures to remember?
Show Answer
32°F is when water freezes, and 98.6°F is normal body temperature. (Other answers: 212°F for boiling water, 100°F for a hot day.)
Question 3: If the temperature goes from 45°F to 60°F, did it get warmer or colder?
Show Answer
It got warmer. The temperature went up by 15 degrees.
Question 4: Name two different types of thermometers and what they are used for.
Show Answer
Possible answers: Weather thermometer (measures outdoor temperature), body thermometer (checks for fever), cooking thermometer (checks if food is safe to eat), digital thermometer (shows temperature on a screen).
Next Steps
- Check the temperature: Look at a thermometer at home or school. What is the temperature right now?
- Keep a weather log: Record the temperature every day for a week. Which day was warmest? Which was coldest?
- Keep learning: In the next lesson, you will learn about Rulers and Scales to measure length and weight.