
Purpose
To develop an understanding of the science behind keeping skin healthy, including how it functions to protect the body and what can be done to protect skin cells from mutations caused by excessive sun exposure.
Context
This lesson is part of the Skin Deep Project, which examines the science behind skin. Skin Deep is developed by AAAS and funded by Neutrogena. For more lessons, activities, and interactives that take a closer look at the science behind skin, be sure to check out the Skin Deep Project page.
Read MoreMotivation
To make sure students understand the basics of cell division, ask them to use the Skin Cancer Investigation student esheet to go to the Biological Basis of Heredity: Cell Reproduction and read about cell reproduction, particularly the somatic cells that are duplicated by the cell division process called mitosis. Students should use the Cell Division and Skin Cancer Investigation student sheet and record their answers to these questions:
- What is the most common form of cell replication?
- (It is mitosis.)
- What are somatic cells?
- (They are body cells, such as those in skin, hair, and muscle.)
- What is mitosis?
- (It is cell division that produces new cells for growth, repair, and replacement of older cells.)
- How many phases of mitosis do somatic cells go through and in what amount of time?
- (They go through six phases in ½ to 1½ hours.)
Next, students should use the student esheet to go to and read the "Introduction and Part 1: Skin Form and Function" in the book The Science Inside Skin. This will introduce the science behind our skin surface and lay the groundwork for the in-class discussion. You also should read these sections in the book. Some studies have shown that students have misconceptions about dark skin providing added protection from the sun, and page 5 in particular discusses skin color.
To measure students' knowledge about skin and skin cell structure, discuss these questions with students during class:
- What is the largest organ in humans?
- (It is the skin.)
- What is the primary function of our skin?
- (Its primary function is to protect our body from infection, dehydration, and to help regulate our body's temperature.)
- How else does the skin act to protect you?
- (It has nerve endings that give us our sense of touch. It tells us when we feel pain, pressure, heat, or cold. It also works with other systems in our bodies to support and maintain the health of cells, tissue, and other organs.)
- The skin has three layers. Do you know what they are?
- (They are the epidermis, the dermis, and the subcutaneous tissue.)
- Do you think skin color provides added protection from environmental elements, like the sun?
- (Dark skin provides more protection against the damaging effects of the sun's UV rays, but these rays can still penetrate cells and cause mutation.)
Development
In this part of the lesson, students will explore healthy skin and the science behind the three layers of skin using the SCI: Skin Cancer Investigation interactive activity. Using the interactive, they will explore the effects the sun has on skin and watch animations about the benefits and risks of sunlight. They also will read about the causes and common risk factors of skin cancer.
Students should use the student esheet and follow instructions to open the online interactive and work through it, stopping to answer each series of questions. You should check for student understanding by discussing these questions in class.
Healthy Skin
- What are the types of cells in the epidermis and how are they related to each other?
- (They are basal cells, squamous cells, and melanocytes. Basal cells divide and form the squamous cells, which reside in the layer above the basal cells. The basal layer contains the melanocytes.)
- What is melanin and what is its role in the epidermis?
- (It is a pigment produced by the melanocytes. It produces the color in skin and protects the skin from the harmful effects of the sun's UV rays.)
- What is keratin and what does it do?
- (Keratin is a protein produced by squamous cells. It reinforces skin cells, which helps protect the skin from nature.)
- What are the two primary features of the dermis?
- (It contains fibers that give skin its strength and elasticity, and it contains sensory nerve cells that give skin its sense of touch.)
- Describe the subcutaneous tissue.
- (It is the bottom layer of skin made up mostly of fat.)
Effects of the Sun on the Skin
- Name the main benefits of sunlight.
- (It provides the energy necessary for life, gives light and warmth to the earth, and helps plants grow. It also can help with depression.)
- What are some of the benefits of the sun's UV rays?
- (They help our bodies produce vitamin D, which is essential for healthy bones.)
- How are these rays harmful?
- (The sun's UV rays can burn our skin, damage our eyes, cause premature aging, and lead to skin cancer.)
Causes
- How do UV rays affect normal cell division?
- (Too much sun on unprotected skin damages cellular DNA, leading to mutations that cause cells to divide uncontrollably.)
- Why do some people have a greater chance of developing skin cancer compared to others?
- (This question should reveal students' misunderstandings about dark versus light skin. Lead students in a discussion about melanin and how even dark-skinned people can get skin cancer and why.)
Tumors
- What are the main differences between benign and malignant tumors?
- (The main differences are: benign tumors are not life threatening while malignant tumors are; benign tumors do not recurr while malignant tumors are recurring; benign tumors do not spread to other parts of the body while malignant tumors can spread; and benign tumors do not interfere with regular body functions while malignant tumors can.)
Skin Cancer: Common Risk Factors
- What are the five most common risk factors of skin cancer?
- (They are actinic keratosis, genetics, environment, complexion, and age.)
- Can a person change his/her risk factors, and if so, how?
- (While risk factors such as genetics, complexion, and age can't be changed, you can reduce [or modify] your risk by doing things such as wearing hats and applying sunscreen to protect your skin, and by detecting and treating actinic keratosis at an early stage.)
- How can where you live increase your chances of developing skin cancer?
- (Sunny locations and high elevations increase exposure to damaging rays.)
- How does genetics play a role?
- (A person is more susceptible to getting melanoma if there's a history of it in the family.)
- What is actinic keratosis and how does it increase the risk of skin cancer?
- (It is a rough, scaly growth that is considered precancerous. If not treated, it can become a cancerous growth.)
Assessment
Discuss in class with students the dichotomy of sunlight—how the sun is necessary for healthy bones and essential to life yet can cause harm and lead to illness and even death. Our society sees tan skin as healthy skin, but it can lead to cancer. What looks like healthy skin to students versus unhealthy skin, i.e., pale skin versus weathered, wrinkly skin? Ask students to examine their own skin. What do they see? How do they envision their skin changing as they age and what can they do to protect themselves from skin cancer?
Finally, ask students to do the "Check Your Knowledge" part of the interactive as a way for them to see for themselves what they have learned.
Extensions
What is the likelihood students will be diagnosed with skin cancer when adults? The lesson, Cancer Risks, describes the environmental and hereditary factors that can lead to diagnosis later in life. This lesson can be particularly important in light of new studies that show that the incidence of skin cancer has doubled since 1994.
Rays of Awareness: Preventing Science Cancer is a lesson from the Skin Cancer Foundation that helps students learn about ultraviolet (UV) radiation from the sun and tanning beds, how it affects their skin, and why protecting themselves from both forms of UV exposure is critical to preventing skin cancer.