Collard greens are the key ingredient in a new science curriculum for middle and high school students.
Chemists Michelle Richards-Babb and Betsy Ratcliff teamed up with researchers from the Davis College of Agriculture, Natural Resources and Design to develop a chemistry curriculum that is inexpensive, accessible and easily duplicated for laboratory courses.
Featured on the February 2017 cover of the Journal of Chemical Education, the article discusses how experiments examining the surfaces of collard greens can help students learn the scientific method.
The experiment featured untreated collard greens, which naturally produce waxy leaves, as well as brushed collard greens with the wax removed.
“I thought it would be useful for introducing chemistry students to the scientific method. They can see right away how the water falls right off one leaf but sticks to the other,” said Richards-Babb, associate professor of chemistry and director of the Office of Undergraduate Research. “The scientific method teaches students how to support their claims with evidence, and this experiment is a relevant way to teach that process. It gets students thinking about why the wax is even there, why it is so easy to brush off and its purpose.”
The wax removal treatment used a paintbrush similar in size to a marinade brush, only with finer, softer bristles. The leaves were then sprayed with water, a technique that demonstrated how removing the leaves’ natural waxy material allows water to stick to them.
The curriculum was piloted in one of Ratfcliff’s Chemistry 112 classes. Students used their smartphones to photograph the results and uploaded them to ImageJ, an open source, free imaging software available from the National Institutes of Health, to examine the water droplets’ shape and contact angles.
“The experiment doesn’t use any chemicals, and you don’t need any kind of advanced instrumentation to measure contact angles,” Richards-Babb said. “This piece of software had been developed by scientists but is really accessible — anyone can download and use it. Students are actually doing science just like a researcher would and using some of the same software and technology they would use. The students always like when you introduce real-world applications in the classroom.”
The laboratory curriculum can also be used to further students’ understanding of more advanced chemical concepts, such as intermolecular forces, hydrophobicity and surface tension while serving as a practical example of issues faced by the agricultural industry, including pesticide use and environmental protection.