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Complete English transcript
Julia, why are you watching the popcorn bowl?
I am waiting for the next kernel to pop.
It looks like a tiny, very quiet piece of corn.
And then, suddenly, it becomes a snack.
Welcome to Curious English, from Your English Toolbox.
Today we are asking a small kitchen question.
Why does popcorn pop?
Make a prediction before we explain.
Is the key ingredient the heat, the water inside, or the hard outer shell?
It is the combination of all three.
Before we explain, let us make four important words clear.
A kernel is one single seed of corn.
For example, one kernel popped before the rest.
Starch is a natural material found in foods such as corn, rice, and potatoes.
For example, bread and potatoes both contain starch.
A shell is a hard outer covering that protects something.
For popcorn, the scientific word for its shell is hull.
For example, a nut’s shell protects the part we eat.
Moisture means a small amount of water inside or on something.
For example, a dry sponge has little moisture.
Now these four words will help us understand what happens inside the kernel.
A popcorn kernel contains a small amount of water surrounded by starch.
A tough outer hull holds the contents inside.
That tough hull acts like a tiny natural container.
As the kernel heats up, the water inside gets hotter.
Some of it turns into steam.
The steam cannot escape easily through the strong hull.
So pressure builds up inside.
To build up means to increase gradually.
Eventually the hull breaks open.
The hot starch expands and quickly cools into the white shape we eat.
That is why a pop can sound so dramatic.
The kernel bursts open.
To burst open means to break open suddenly.
Popcorn also needs enough moisture inside the kernel.
If a kernel becomes too dry, it may not pop well.
That small amount of water is vital.
It is not the same as pouring water into the pan.
Right, the important water is already inside the kernel.
Let us review our three expressions.
Pressure can build up.
A shell can burst open.
And the kernel needs enough moisture.
Your turn.
When steam cannot escape, what gradually increases inside the kernel?
Pressure builds up.
What does the kernel do when its shell breaks suddenly?
It bursts open.
And what does a kernel need enough of to pop well?
Moisture.
On our episode page, practise these four words with an example for each one.
You will also find a quick check to test what you remember.
The link is in the description.
Keep your English curious.
And do not stare at the bowl too intensely.
