Science Smarts: Pop secrets

By Patty Rooks on August 16, 2025.

I love to sit down and enjoy a nice big bowl of popcorn some evenings and watch a good movie. Have you ever wondered what makes these tiny little seeds actually pop into a magnificent fluffy treat? Of course, we had better investigate this further! Let’s get started!

*Remember to ask an adult before doing this experiment.

Materials

– Popcorn seeds

– Baking sheet

– Ruler

– Measuring cup

– Oven

– Popcorn popper

Procedure

1. Measure out about a quarter cup of popcorn seeds; count the number of kernels in this batch.

2. Count out a second batch of seeds with the same number of seeds as your first batch.

3. Spread out one batch of the seeds on the cookie sheet and cook them for 90 minutes in a 200°F oven.

4. Pop the other batch in the popcorn popper. Let them cool a bit then count the number of kernels that did not pop. Now pick ten of the popped kernels and measure how long they each are. Now add up the number and then divide by ten to find the average length of one kernel. Write down your findings

5. Eat your popped popcorn while you wait for the other ones to cook!

6. After 90 minutes take the kernels out of the oven, an adult should probably do this for you. Let them cool.

7. Pop your second batch of popcorn. After they have cooled a little bit count the number of unpopped kernels. What do you find?

8. Measure 10 kernels from the second batch the same as you did with the first.

9. Compare your results. What do you find?

Explanation

Did you know that even though they seem really hard, that there is moisture inside a popcorn kernel, and that is what makes it pop. If you were to cut a kernel open you would find that the inside of the kernel contains the new seed, it is a soft moist material. It is moist to stay alive until it is ready to sprout in the right conditions. When you pop the popcorn, you are heating it very quickly and causing the moisture to quickly vaporize into steam expanding rapidly. This expansion causes the jacket of the kernel to burst and the material inside puffs out, almost like a jack-in-the-box.

When we heat the popcorn slowly as we do in the oven we are slowly removing the moisture from inside the kernel, so when we go to pop it there is nothing to expand inside the kernel, thus why the kernels of the second batch aren’t as big, and why less kernels should have popped.

Mark your calendars for the praxis AGM on Wednesday, Sept. 17 at 7 p.m. We are always looking for new board members who want to share their love of science. Contact Praxis for further details.

Patty Rooks, senior scientific consultant Praxis Science Outreach Society. Praxis has moved! We are very fortunate to be located in the Community Futures Entre Corp Building at #202 556 Fourth St. SE, Medicine Hat, Alberta, T1A 0K8. For all your science needs, please email praxis@praxismh.ca.

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