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## Measuring and Protecting Skin

Author(s): Nancy P. Moreno, PhD, Barbara Z. Tharp, MS, and Judith Dresden, MS.
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#### Session 1: Estimating Surface Area

In this activity, students will compare and contrast their own skin with that of an orange. Students will make observations and predictions, estimate, calculate, graph, and draw conclusions based on their investigation. They will discover that skin protects inner tissues of the body and is a vital organ that must be protected from sun damage.

1. Have Materials Managers collect the materials for their groups. Begin the activity by having one student in each group list the group’s observations about the orange skin. Then place a check mark next to any observation that would be the same for human skin.

2. Ask students, How much skin does an orange have? How could we find out? Direct students to estimate the amount of skin on their oranges, in cm squared, and then color in the corresponding number of squares on a sheet of graph paper. They may want to measure their oranges using tape measures. With older students, use this opportunity to investigate the relationships among diameter, circumference, and area. Ask, How could you check your estimates?

3. Have groups peel their oranges and trace the peelings onto graph paper. Have them color in the traced areas in orange. Then, instruct students to count or measure the number of squares, and the area colored in orange. This will enable them to determine how much skin their orange really has. Allow students to devise their own methods for counting partially colored squares, or instruct them to count every other partial square.

4. Ask, Are you surprised by the area covered by the skin of your orange? Why or why not? Next, have the students examine the peeled oranges.

### National Institute of Environmental Health Sciences, NIH

My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932

### Houston Endowment Inc.

Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education