When I was growing up, I feared lizards. My brothers would sometimes chase them, and their tails would fall off. The lizards scampered away, leaving a wriggling tail behind. I felt sorry for the lizards, but the wriggling tails scared me, too.
Another thing that bothered me were the lizards climbing the walls and the ceilings at our house. I was always afraid that a lizard would fall on me while I was asleep. It would be terrible if one fell into my open mouth!
If house lizards bothered me, I was horrified by geckos. They made loud sounds, even in the middle of the night, and scampered up trees to stare at me. One night, we were staying at a guest house at an academy, and the bathroom was outside. As I made my way out, I noticed, perched on a papaya tree near the window, the largest gecko I had ever seen. I rushed back into the bedroom, waking my husband up and vowing not to go back until the “beast” was gone.
Despite my dislike of lizards, I wondered: how do geckos (which are a type of lizard) scale walls or trunks of trees and walk upside down on ceilings without falling? What makes their feet stick to smooth and even rough surfaces?
After years of theorizing, scientists found that geckos have hundreds of thousands—or even millions—of brush-like structures on their feet called setae. The tiny setae increase adhesion through weak electrostatic forces (Van der Waals forces) that attract neutral substances to one another. So, a gecko’s “stickiness” is really all about chemistry. These forces occur only over infinitesimally short distances. The setae have even smaller divisions at their ends called spatulae, which are similar to the kitchen tools used to flip omelets or pancakes.
The geckos can break the attraction by lifting their toes quickly and don’t even leave marks where their toes were before. Using ideas from gecko feet, scientists and engineers are working on special types of glue, bandages that don’t require stitching, robots that can climb walls, and wall-climbing pads.
Just as the power of adhesion in gecko feet lies in weak Van der Waals forces, our “power is made perfect in weakness” (2 Corinthians 12:9). The Bible also says that “when I am weak, then I am strong,” since God’s power in us makes us strong (2 Corinthians 12:10). The adhesive power of gecko feet teaches us to rely on God. His power in us will allow us to overcome temptations and problems in life. It will prevent us from sinning against Him. We need to plug into God’s power every day.
Below is an activity you can use in class to demonstrate electrostatic forces.
Activity: Van der Waals Forces/Electrostatic Forces
Scientific Principle: Unlike charges attract, while like charges repel.
Materials: balloons, empty soda can, smooth wall
Directions:
- Blow up a balloon.
- Rub the balloon on your hair for 20 seconds.
- Place it near the wall. Observe what happens.
- Rub another balloon on your hair for 20 seconds.
- Place it near an empty soda can. Observe what happens.
- Blow up two balloons. Hang them on a string from the ceiling. Rub both balloons on your hair for 20 seconds. Observe what happens when you put the balloons close to each other.
Discussion: When you rub a balloon on your hair, it acquires negative charges. The wall is positive. Since opposite charges attract, the balloon will stick to the wall. Explain what you observe from placing the balloon near an empty soda can or when you put two balloons that you have rubbed on your hair close to each other.
Author
Ophelia Barizo
Barizo, M.Sc. is a nationally certified STEM educator with over 35 years of experience as a science teacher and five years as a STEM Coordinator for the Chesapeake Conference. A passionate advocate for science education, she was recognized as an Albert Einstein Distinguished Educator and has mentored countless students and teachers in the pursuit of excellence in STEM learning. Now retired from full-time teaching, Ophelia continues to serve as a STEM consultant, sharing her expertise with schools and organizations committed to advancing STEM education.