Student Learning Objectives:
- Explain how size, structure, and scale relate to surface features
- Describe the function of compliant surfaces with regard to adhesion
(What happens when a surface of an object is applied to the surface of another object?)
At a Glance for Teachers:
- Mini-Me Activity (optional)
- Visualization and diagramming of surface of gecko foot at various scales
Note: Some questions in the Student Journal are underlined as formative assessment checkpoints for you to check students’ understanding of lesson objectives.
Vocabulary: Adhesive, Compliant, Lamella, Seta, Spatula, Surface Terrain, Topography Refer to the end of this Teacher Guide for definitions.
- PowerPoint for Lesson 4
- Student Journals for Lesson 4
- Computer with LCD or overhead projector
- Transparent tape
- Pipe cleaners (for Mini-Me optional activity)
- Measuring tape (for Mini-Me optional activity)
- Modeling clay (for Mini-Me optional activity)
Student Journal Page #
Teacher Background Information and Pedagogy
Slides 1 & 2
Student Journal Page: 4–1
By definition, an adhesive is any material that will be useful in holding two objects together solely by surface contact. For an adhesive to achieve extremely close contact with an object, it must have the properties of a liquid, which makes it capable of coming into intimate contact with the surface. In use, an adhesive must be able to resist any applied force that attempts to break the bond formed between it and the object or surface to which it was applied. In other words, it will need the properties of a solid.
Adapted from Johnston, J. (2003). Pressure sensitive adhesive tapes. Pressure Sensitive Tape Council. Northbrook, Illinois, Page 23.
1. Provide each student with a piece of transparent tape.
“Observe the transparent tape on a smooth surface, like a desk. Place the tape on the surface and “rub” out as many of the bubbles as possible. Use a pen to circle the bubbles on the tape. Place the actual tape onto the journal page 4–1 with the bubbles marked.”
Student Journal Page: 4–1
2. Based on student observations and this text, ask students questions similar to these below. Solicit from the students their ideas about the properties of the tape. Draw out the properties of solids and liquids and explanations for what makes the tape work.
“Would you consider the tape stuck to a surface to be an adhesive? Why or why not?”
“Work in your small groups to describe how transparent tape has the properties of both a liquid and a solid.”
3. Ask the students the following:
“Recall the activity we did with the shoes. What forces exist between each pair of surfaces?”
“Tape and smooth surface”
“Shoe and floor”
Students might say “adhesive force” for the tape and “gravity” for the shoe.
“Which surface to surface interaction do you think is most similar to a gecko climbing a wall? Explain your answer.”
Allow students to explain their response.
4. Note to teacher: For image 4.3, point out that two compliant surfaces would come into even closer contact than one compliant surface with a hard surface.
5. The Gecko Up-Close Activity: A gecko can “stick” or adhere to just about any surface from a single toe. Ask the students to make predictions.
“We are going to be making some close-up observations of the surface of the gecko’s foot. Before we take a closer look, predict what you think the surface of the gecko’s foot looks like at the nanoscale level.” Solicit student predictions without comment.
“Let’s take a closer look at the foot of a gecko. Each of the following images takes a progressively closer look at the foot of a gecko.”
Student Journal Pages: 4–2 4–3 4–4 4–5
Teacher Background Information: The following description of the anatomy of a gecko’s toe is adapted from “The Life of Reptiles Volume I” by Angus Bellairs:
Optional Hands-On Activity: Use the Mini-Me activity located at the end of this teacher guide (courtesy of the University of Wisconsin, Madison) to provide students with the experience of picturing themselves much smaller than what they are and then sculpting an image that symbolizes their understanding of the invisible world. Once students have built their mini-me, have them proceed to the student journal page 4-2.
6. Working in pairs, students should respond to the journal prompts and visualize what it would be like to shrink down to these scales and interact with the various structures. Tell them to be creative with their drawings, but also to be as accurate as they can when they “enter” this new world. Provide an example of the first sketch on the board. Students may describe the “view” as appearing like hills and valleys. Below is a sample student drawing depicting the centimeter scale from the field test.
Optional: You may want to add some discussion about what makes a good scientific drawing.
7. Use the slides at the end of the PowerPoint of this lesson to illustrate a field test student’s for each magnification.
As you introduce the four images on this slide, you may wish to use the following descriptions and explanations:
Image (a): “The toes are lined with deep ridges.”
Image (c): “At the next higher magnification, one can see that the tiny projections are actually flattened on the end.”
“It has been estimated that a gecko has a total of about one million setae on all its feet.”
7. Ask the students:
“As the scale decreased, what did you find out about the structure of the gecko’s toe?”
As the scale decreased, more and smaller structures became evident in the images.
8. As a culminating discussion, ask students to respond to the questions in “Making Connections.”
“Let’s review briefly your understanding.”
1. “Describe one or two ideas that you learned during this lesson.”
2. “Which range do gecko setae fit into?”
3. “Which force would make best use of these many points of contact?”
4. “How might the gecko’s foot structure help the gecko climb a wall or ceiling?”
Make sure to talk with the students about the structure of the gecko’s foot being compliant with a surface.
9. The end of each lesson contains this flow chart that provides an opportunity to show students the “big picture” and where they are in the lesson sequence. The following color code is used:
Yellow: Past Lessons
Blue: Current Lesson
Green: Next Lesson
White: Future Lessons
Appendix: NanoLeap Physical Science Vocabulary
Something that tends to remain in association or attachment
- Soft and able to conform to the surface of another object
- Yielding to physical pressure
Lamella (Lamellae plural)
Each gecko toe pad is covered on its under surface by rows of wide scales
Seta (Setae plural)
Spatula (Spatulas plural)
The setae branch and sub-branch several times; the final twigs end in a pair of minute flattened tips called spatulas
The physical features of a surface, usually referring to the topography
- The physical or natural features of an object and their structural relationships
- The depths and rises on a surface
To understand the concept of scale
To relate to changes in scale
To learn how to accurately measure length and height
Construction of a Mini Me
Crayola Modeling Clay
Investigating Static Forces in Nature: The Mystery of the Gecko
Lesson 4: What Do We Learn When We Look More Closely?
© 2009 McREL