STR Micro-Lesson: Warning - This Lesson May Cause Tooth Decay
(click here or on image to see an enlarged version)
Question
The hairy fibers above are often found at summertime county fairs and state fairs as well as at circuses. It may look like animal fur, but it’s not. What is it?
Answer
The image is of cotton candy, viewed at 100x with a handheld digital microscope such as STR’s “ProScope HR2”. Cotton candy is not from the cotton plant at all, but a special form of sugar (sucrose) which looks and feels like cotton or wool because of the special way it is made.
Micro-Lesson* Plan
Topic: Food Science – Chemistry
Download the enlarged version of the image above and show it to your class (using a projector or a color printout). Ask the question just below the image. You may wish to give hints.
Once you have elicited or presented the answer, explain to students that ‘natural’ sugar is a product of photosynthesis in plants which produce the sugar for energy. Plant sugars are extracted and manufactured by people into various forms as food sweeteners and candy, including cotton candy. Show students the image below of granulated white sugar captured with a hand-held camera microscope at 100x magnification.
(click to enlarge)
Notice the crystal structure and general hexagon shape determined by the sucrose molecule. When the sucrose is heated, the chemical bonds are broken and a sticky solution (of glucose and fructose) is formed that can be stretched into a very thin strand which keeps its shape when cooled. Many foods, especially desserts and other sweet treats, rely on chemistry to exist. Think about that at the county fair while you enjoy the cotton candy sugar melting on your tongue!
An introduction of the history of sugar production and trade is a colorful and interesting social studies extension to this lesson. These links may be helpful:
Exploratorium: Science of Sugar
Map of U.S. Sweetener Production
More…
See more great lesson resources
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Comments?
Let us know what you think of this lesson idea, or if you have suggestions for more STR Micro-lessons.
*STR Micro-Lessons™ are designed as "plug-ins" to support and augment standards-based science teaching and learning. For complete lessons using the Scope on a Rope handheld digital microscope, see the STR Teacher Resources page.
