Click on the following links or scroll down to view the pages. Return to other themes.
Test Your Knowledge About Temperature!
1. What is temperature?
a) How fast the molecules in an object are moving
b) How hot or cold an object feels
c) None of the above
d) Both A and B
2. Which instrument is used to measure temperature?
3. Which temperature is warmer: 32 degrees Fahrenheit, 0 degrees Celsius or 273 Kelvin?
a) 32 degrees Fahrenheit
b) 0 degrees Celsius
c) 273 Kelvin
d) All of the above
4. What is the melting temperature of chocolate?
a) 120 degrees Fahrenheit
b) 98.6 degrees Fahrenheit
c) 0 degrees Fahrenheit
d) 500 degrees Fahrenheit
5. What is the lowest temperature ever recorded on Earth?
a) 100 degrees Fahrenheit
b) 0 degrees Fahrenheit
c) -129 degrees Fahrenheit
d) None of the above
Hot or cold: Are our fingers accurate thermometers?
Most of us define temperature as how hot or cold something is. But what scientists really measure with a thermometer the average amount of heat in an object — the energy generated from the molecules moving within it. Molecules that are close together or moving very fast generate more heat, which makes an object’s temperature higher. In a cold object, molecules move slowly and may be spread farther apart.
Heat can move from one object to another, including to and from our bodies. We can sense how hot or cold something feels, but can our bodies accurately measure the temperature? Try this activity to find out.
- Three cups of equal size
- Very warm (but not hot) water
- Cold water with ice
- Lukewarm (room temperature) water
- Two thermometers
- Your fingers
What to do:
- Fill one cup with very warm water, one cup with cold water (add ice if you have it), and the third cup with lukewarm water.
- Place your left finger into the very warm water and your right finger into the very cold water.
- Leave your fingers in the water for about 15 – 30 seconds, until they feel accustomed to the water temperature.
- Take both fingers out and place them into the third cup (of lukewarm water) at the same time. What do you feel? Did both fingers feel the same when you put them in the third cup? Do you think your fingers accurately measure temperature?
- Repeat the experiment using two thermometers instead of your fingers (make sure both thermometers give the same reading before you put them in the water — if they are different, make note of the difference between the two). Record the temperature of the warm and cold cups of water. Then, place both thermometers in the third cup at the same time and record the temperature after 15-30 seconds. Do the thermometers agree? Do your fingers make accurate thermometers?
Through our sense of touch, our skin can feel whether or not heat is moving into or out of our bodies — that is, we feel how hot or cold the water is. When you placed your fingers in the warm and cold water, you felt heat energy moving into (warm) and out from (cold) your skin. However, what you felt was relative to how hot or cold your skin felt before. Temperature measures the average amount of heat in an object (energy generated by its moving molecules). We feel the transfer of heat energy between our bodies and another object, but our bodies do not accurately measure temperature like a thermometer does.
We can feel heat loss from our skin during a cold winter day. When the wind starts blowing, it can make us feel colder by taking the heat away from our bodies at a faster rate, even though the air temperature hasn’t changed. Visit the Did You Know page to learn more about “wind chill.”
Activity based on Hot Finger – Cold Finger: What Does Temperature Tell Us? from the Seaford, Delaware School District. Image courtesy of the National Park Service.
How cold does it feel outside? Calculate the wind chill to find out.
While most of us check the thermometer to find out the outdoor temperature, wind also affects how cold it feels outside.
When it is windy, heat is carried away from our bodies at a faster rate, meaning that body temperature drops more quickly. The “wind chill” temperature indicates how cold it feels to people and animals when wind speed is factored in with temperature. Meteorologists use a chart to calculate it (click for a bigger image).
You can calculate the wind chill in your area by entering your “City, State” on weather.gov to find the current outdoor temperature and wind speed where you live. Then enter these values into the wind chill calculator.
Image courtesy of National Weather Service.
Learn fun facts about temperature!
- Temperature measure how hot or cold an object is, based on the energy generated by the molecules moving within it (heat). It can be measured in Fahrenheit (°F), Celsius (°C) or Kelvin (K).
- The highest temperature ever recorded in the United States was 134 °F in Death Valley, California. The lowest recorded temperature in the United States was -80°F in Alaska in 1971.
- According to Bill Nye the Science Guy, an egg will cook on a surface that’s 130°F. During the summer, a sidewalk can get hotter than the air, sometimes up to 150°F — hot enough to fry an egg!
Sea Surface Temperature (SST) is the temperature measured at the surface of the ocean. Scientists use satellites and buoys to record SST around the world. Here is a satellite map showing global SSTs in 2002 (red is warm, blue is cold).
First image courtesy of Kansas Department of Health and Environment. Second image by MJ Cavallo, courtesy of U.S. Library of Congress. Last image courtesy of the National Oceanic and Atmospheric Administration.
Check out these cool tips and tools about temperature!
Tips for Learning More
- Learn more about temperature at Weather Wiz Kids
- Check the local forecast before you head outdoors
- Learn how to dress warmly for winter wind chill
- Make your own thermometer
- Learn about melting points by taking the temperature of snow
- Find out how heat affects sugar cubes
Global air temperature image courtesy of NASA Earth Observatory.
Cool Online Tools
- Calculate wind chill
- Check out the current air temperature map of the United States
- Report and predict weather by playing the EdHeads Weather Game
- Learn about the Heat Index and how to stay safe from hot summer temperatures
- Look at a cool diagram showing how temperature changes throughout Earth’s atmosphere
Windchill image courtesy of National Oceanic and Atmospheric Administration.
1) d. Temperature measures the movement of molecules within an object, which results in how hot or cold that object feels. It is different from heat, which is energy that is moved between one object and another.
2) b. Your doctor uses a thermometer to measure your body temperature when you are sick. Scientists use a thermometer to measure the temperature of the air, water and other substances. Hygrometers, barometers and anemometers are used to measure humidity, air pressure and wind speed, respectively.
3) d. All of these represent the temperature at which water freezes. Temperature can be measured using different scales: Fahrenheit, Celsius and Kelvin. On the Fahrenheit scale, water boils at 212 degrees and freezes at 32 degrees. On the Celsius scale, water boils at 100 degrees and freezes at 0 degrees. The Kelvin scale is based on absolute zero – the temperature at which molecules in an object stop moving. Scientists and most countries use the Celsius scale. The United States used the Fahrenheit scale.
4) b. The melting point of chocolate is about the same as the human body – 98.6 degrees Fahrenheit. That’s why chocolate melts in your mouth! However, in order to melt all the crystals that form from cocoa butter (one of the main ingredients) chocolate needs to be heated to about 120 degrees Fahrenheit.
5) c. The lowest temperature ever recorded was -129 degrees Fahrenheit (129 degrees below zero). It was recorded at the Russian research station Vostok in Antarctica on July 21, 1983, during the middle of Antarctica’s winter. Scientists working in Antarctica must use extreme safety in going outdoors, including wearing many layers of special protective clothing and leaving no skin exposed to the air!