Seed of the Week: Popcorn Science

As several people recognized, our mystery seeds from last week were indeed popcorn.

(Photograph of popcorn on cobs from Wikimedia)

The scientific name for popcorn is Zea mays L. subspecies mays, according to the USDA plant name database. On the Internet, you may find it as the synonym Zea mays var. or subspecies everta. You will also encounter the names Zea mays var. everata or yet another synonym, Zea mays var. praecox. Although it is confusing, the bottom line is that popcorn is a type of corn.

(Photograph of Corn by Petr Kratochvil)

Popcorn grows on stalks like the ones shown above. The male, pollen-producing flowers or tassels are on the top and the female "ears" below. The silk of the ears capture the pollen grains, which is when pollination occurs. The seeds develop within the husks of the ears, on the cob. When the plant turns brown and dry, the popcorn is harvested.

Science Activities With Popcorn

Did you know popcorn is a perfect tool for science exploration with kids? Even though we think of popcorn as a fun snack, you can carry out serious science experiments with it.

1. Compare the germination of beans and popcorn (dicot plants versus monocot plants).

Gather:

  • Dry bean seeds, especially big types like lima beans, available in the in the grocery store in the dried food area. (Be aware that seeds intended for gardening may be treated with chemicals.)
  • Popcorn, preferable on the cob (sometimes available in the grocery store as well)
  • Paper towels
  • Water
  • Plastic sandwich bag, paper plate covered with plastic wrap, or plastic cup with plastic wrap to cover, one per participant

First, have the children explore the seeds and compare the popcorn with the beans. How do the different seeds look? What color are they? What shape are the different types? Do they smell? Are the seeds hard or soft? Do they seem to have an outer covering? Have older children open some seeds and look at them under a microscope. If appropriate, encourage the children to write down their findings.

Wet paper towels until damp, not dripping wet. Note: you will need to keep the paper towels wet throughout the experiment. Try to avoid handling too much, as the paper may begin to grow mold. You may add soil to the center of the cups, but again that increases the chance for mold growth.

For plates or plastic bags:

Lay the paper towels flat. Place bean seeds and popcorn seeds inside the towel. Fold the top over, creating a sandwich with the seeds inside. Slip the paper towels into a plastic bag and close, or onto a paper plate and cover with plastic wrap.

For the plastic cups:

Press the paper towels into the cups and against the sides. Slip the seeds between the towel and side, so the children can see them. Cover with plastic wrap to prevent drying.

Depending on the temperature, the beans should start to swell and a root start to form as early as 24 to 48 hours later. Show the child how to slip open the two halves of the bean, called the cotyledons (the food storage part of the seed - they are the dark purplish structures surrounding the leaves in the photo below) and observe the newly emerging plant inside. The popcorn may take up to a week to germinate. Compare the bean seeds, which have two cotyledons to the popcorn seeds, which have only one cotyledon (monocot). Why might seeds take different lengths of time to germinate?

Open a few every day to see how the new plant grows. Allow the children to experiment with the seeds. They might want to remove portions of the plant or seed or change the growing conditions (moisture, light, add soil) to see what happens.

2. The Science of Popcorn:   The Pop!

Check out this video of a kernel of corn popping:

Ever wonder how a small, hard kernel could become fluffy white popcorn? Let's find out more.

Requires adult supervision.

Gather:

  • at least 1 cup of popcorn kernels (not popped)
  • three bowls,
  • a hot air popcorn popper (or other method for popping corn)
  • a cookie sheet
  • a measuring cup
  • water and access to a sink or another large bowl
  • a colander
  • paper towel
  • easily removable tape, such as painter's tape
  • a pencil or pen, and paper to record your results
  • access to an oven
  • timer or clock
  • oven mitts

Preheat the oven to 200° F. Label the bowls with tape.

  • Bowl 1 - wet
  • Bowl 2 - dry
  • Bowl 3 - control

Start by placing 1/3 cup of the popcorn kernels in bowl 1. Add one cup of water and then set aside for one hour.

Spread 1/3 cup popcorn kernels on a cookie sheet and place in the oven for one hour. Check periodically to make sure they are not burning.

Pop 1/3 cup popcorn kernels and catch the results in bowl 3 (control).

After an hour, drain bowl 1 by dumping the contents into the colander (over a sink) and dry the bowl and kernels with a paper towel. Pop it in the same manner as you did for the control. Catch the results in bowl 1.

Using oven mitts, remove the cookie sheet from the oven. Have any kernels popped? Now pop the dried kernels and catch the results in bowl 2 (dry).

Measure the amount of popped corn in each bowl using the measuring cup. Count the number of kernels that did not pop. Look at the texture and size of the kernels.

In general, the more moisture the kernels contained, the more steam they produce and the better they should have popped. Can you have too much water? Try leaving 1/3 cup of popcorn in water overnight. How does this affect the kernels’ ability to pop?

You can expand this experiment by comparing different brands of popcorn.

Hope you have fun. Please let us know if you have any questions. We would also love to hear what you find out.

Other places to find out more:

A group called Naked Scientists have some great videos and more information about Popcorn Steam Explosions.

Kennesaw.edu has a whole bunch of popcorn activity links ( a few were broken)

Popcorn.org has an extensive Popcorn Teaching Guide, complete with a free poster to download.

Popcorn (Charlesbridge)by Elaine Landau and Brian Lies, with illustrations by E. Landau
The Popcorn Book by Tomie dePaola

Corn by Gail Gibbons
An adult nonfiction title:

Popped Culture: A Social History of Popcorn in America by Andrew F. Smith

Sources of seed at Amazon:

100 Strawberry Popcorn Seeds for Planting in the Small Garden

Cutie Pops Popcorn - 100 Seeds - Multicolored Miniature
David's Popcorn Corn Robust 997 300 Seeds per Packet

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