Today I am… learning about expansion and contraction
So I can… understand how it relates to heat
I’ll know I have it when… I can explain expansion and contraction using the Particle Theory
The estimated time to complete this lesson is 1 hour
You should be able to answer these questions:
Can I use the particle theory to explain what is happening to objects as they expand and contract?
Can I give a reason why expansion and contraction is important in our everyday lives?
Last lesson we learned about the particle theory of matter. Try to answer these questions before we begin today:
Heat is a form of what?
What causes particles to move faster or slower?
What do you think would happen to a piece of matter if we heated it?
Atoms + Energy = ?
Draw what the atoms would look like before and after the heat is added
When objects are heated, the particles:
gain energy
move faster
need more space
Because the particles need more space, the object expands
Expansion increases the volume which makes the object “get bigger”
The particles do not get bigger, the distance between the particles gets bigger
When objects are cooled, the particles:
lose energy
move slower
need less space
Because the particles need less space, the object contracts
Contraction decreases the volume which makes the object “get smaller”
The particles do not get smaller, the distance between the particles gets smaller
To help remember the difference between expansion and contraction, you can think about when you breathe.
Take a deep breath and feel your lungs get bigger. Your lungs are expanding as they fill with air.
Now slowly let your breath out and feel your lungs get smaller. Your lungs are contracting as the air leaves.
You can also think about balloons.
When you blow them up they expand
When you let the air out they contract
When matter expands it gets bigger and when matter contracts it gets smaller. It is hard to see objects expanding and contracting with our naked eye because these changes are usually so small!
What happened to the liquid when we placed the thermometer in warm water?
What happened to the liquid when we placed the thermometer in cold water?
Liquid thermometers work because the alcohol inside expands and rises when it is warm outside, and the alcohol contracts and falls when it is cold outside
We know that when it is cold or there is a lack of heat energy the particles move slower and the matter contracts.
However, water is the only substance that expands when it gets cold.
Have you ever put a water bottle in the freezer and forgot about it? What about a can of pop?
What happened to these objects in the freezer?
We encounter expansion and contraction throughout our everyday lives. It is really important to understand how the particles in matter act when there is a presence or absence of heat energy.
To help you learn more examples of expansion and contraction and why it is important, there are three short videos for you to watch. While you are watching these videos, try to answer the questions that go with each video. These questions can be found in the worksheet to the right and below each video.
Make sure that you understand what is happening to the matter at the particle level. What are the particles doing that makes the matter expand or contract?
Questions to think about while watching:
What was happening to the water particles to cause the balloon to inflate?
What was happening to the water particles to cause the balloon to deflate?
Questions to think about while watching:
What happened as the iron rod was heated? Why did this happen?
What is a job that has to think about expansion and contraction? Why do they have to think about it?
Questions to think about while watching:
Why did placing the ping pong ball in hot water remove the dent?
What are three instruments that use the expansion and contraction of matter to work?
Explain how a thermometer tells us the temperature outside.
You are FaceTiming your friend who lives in Australia. They tell you that when they went for a walk today the telephone wires were really tight, not sagging. Your friend asks you if you know why this is happening.
You have been hired by the local newspaper to write answers to the science questions that students have submitted. Choose two of the questions below to explain in your own words. They must be different states of matter. For example, this means that you cannot pick two questions about solids.
Why does an engineer need to think about expansion and contraction when designing a bridge?
Why does my mom run her hand under hot water when she tries to get her ring off?
How is a liquid thermometer able to measure the temperature outside when it is summer and winter?
Why do telephone wires sag in the summer and are tighter in the winter?
Why does a balloon placed in dry ice shrink but when it is removed it returns to its original shape?
No matter what questions you pick, you need to make sure that you are writing in full sentences. These are some words that should be included in your answers:
particles
expansion
contraction
heat energy
One of your answers should include a drawing. Be creative with your answers! You can make up the identity of the student who submitted their question, you can give your column a headline and can make up a name for your column such as “Ask Andy”, “Angie’s Answers”, “Kevin Knows it All” or “Science with Sarah”.
Alex is trying to get the metal lid off of a jar. Should you tell Alex to put the lid under hot or cold water? Why?
Try to include the words expansion and contraction in your answer!
Make sure you can answer these questions so you know you have a good understanding of the material! Try to answer these questions before moving on to the next lesson:
What causes objects to expand? (make sure you use the word particles in your answer)
What causes objects to contract? (make sure you use the word particles in your answer)
What is one reason why it is important to know about expansion and contraction?
Take the quiz to make sure you are on the right track!
David Chiu. (2014, January 17). Charles' Law - Balloon blown up in a flask. https://www.youtube.com/watch?time_continue=19&v=QjDJgF9H580&feature=emb_logo
LiacosEM. (2019, February 23). Thermal Expansion of Solids and Expansion Gaps in Bridges. https://www.youtube.com/watch?v=PaH2WU3Wt-4&feature=emb_logo
Learning Port Interactive. (2019, August 5). The Uses of Expansion and Contraction of Matter in Daily Life. https://www.youtube.com/watch?v=T1zFwgj2mZ4&feature=emb_err_watch_on_yt
Nelson Thomas Learning. (1999). Nelson Science & Technology 7.