Bodily Defenses Image Map

Activity 1: Skin Observations

This activity will focus on the first line of bodily defense: the skin! Students will complete observations and answer questions about their own skin as well as the skin of others. They will complete an experiment to examine the absorption of certain materials on the skin.

Eye dropper, water, hand lotion, mineral oil, rubbing alcohol
Student Observation Journal for Activity #1 (right mouse click and select "open in a new window" to open as a MS Word document)

Learning About Skin
To learn about the chemical properties of skin, you can put various substances on the outer surface and observe what happens. Some substances just stay on the surface, while other substances disappear (dissolve) into the skin.

1. Make predictions/hypotheses on your observation journal page about what each of the substances will do once they contact skin.

2. Turn your arm so that your palm is facing up. On your forearm, put a drop of water. Next to it, put a drop of lotion on your skin. Next to that place a drop of mineral oil. Finally, place a drop of rubbing alcohol on your skin. You should have 4 different substances on your skin. Spread out each drop on your skin to increase the surface contact of the various liquids, but do not rub them in. As you do so, be sure NOT to mix the substances together.

3. Watch all four drops for 10 minutes without disturbing them. At the end of ten minutes, record your observations, including how the substances made your skin feel (oily or not, change in temperature?) and any changes to the substances.

4.  Which substances were absorbed by your skin? Which substances stayed oily? Record your observations.

5. Answer follow-up questions on the Q/A response sheet using what you've learned from this experiment and also reflections from the "How We Find Out" section of this unit.

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