This popcorn science project investigates how popcorn works.  Ever wonder how those hard little kernels of corn pop into the soft puffs?  Before starting, if you are not sure how to properly conduct an experiment, you can find out how by following our experiment guide. 

First: remember to get permission first if you are not allowed to use the stove without supervision.

Why does it pop?

The short story is that a typical un-popped kernel contains a small amount of water in its center.  When heated quickly enough, the water inside the kernel turns into steam.  The steam pushes against the inside of the kernel as it gets hotter and eventually the pressure from the steam overcomes the strength of the kernel and pops it.  The explosion causes the soft tissue inside the kernel to puff outwards, giving a popped kernel its characteristic appearance. 

Well, lets assume for a while that we’re not sure that this is what happens and are merely hypothesizing.  How could we prove our hypothesis?  Why experimentation of course!  The fun part of any popcorn science project.

The Control

First things first: perform a control.  Get some popcorn and pop some of it, get a rough estimate of how much of it popped and how much did not. 

Experimentation

Now, what if you warm up the popcorn in a 220 degree oven for a couple of hours and then try to pop it?  Does it still pop?  As you might guess, it does not, but why?  The answer lies with that little bit of water inside each kernel.  When the kernel was heated at the relatively low temperature, the water inside dried up.  So trying to pop these dried out kernels will be fruitless – without the water at the center of the kernels, popping will not be possible.

What other experiments could be run to further convince yourself of your hypothesis?  Here are some ideas: 

·        Soak the kernels for a few hours, and then try to pop them.  Will the extra water help or hinder the kernels in popping?

·        Will any kernels pop if they are heated below the temperature at which water turns to steam?

·        Score the kernels.  If you pierce the hard shell of the kernels, how would that affect their ability to burst from the steam pressure?

·        Does freezing the kernels have an effect?

Further Information

When you perform these popcorn science project experiments, don’t forget to take a guess (hypothesis) as to the outcome of the experiment before you do one.