While many early Americans believed that popcorn (the ancestor of all corn) popped because a tiny angry spirit who lived inside the kernel wanted to escape, today's scientists think otherwise. They've learned that the extra-strong hull (outer covering) on a popcorn kernel seals in water that forms in the moist, pulpy center. When the kernel is heated, the water boils and turns to steam and expands. Finally, the pressure builds high enough for the kernel to explode, and the fluffy endosperm fuses and fills with air. Imagine the exploratory potential in a popcorn unit. For instance:
* Experiment to determine how moisture content affects the kernels' popping ability (dry some kernels, freeze some, soak some, and so on).
* To see how well students understand popcorn physics, challenge them to prevent a popcorn kernel from popping (e.g., they might puncture the outer covering or dry it out first).
* Compare two different brands or types of popcorn, starting with 100 kernels of each, and record and chart the number of kernels that popped, number that didn't pop, volume, flake size, and so on.
* Predict, then experiment to find out whether corn seeds or popped corn weigh more. How do the volumes compare? How can you explain your findings?
* Research the different ways in which early Americans popped corn: For instance, on a stick over the fire, or in sand in clay pots. Write fictional stories detailing how popcorn's ability to pop might have originally been discovered.
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