Lesson Title: How Your Body Protects You from Germs
by:  Debbie Bartsch
Grade Level: Elementary

Goal: To provide an experience for students to see how mucous membranes help prevent germs, and other objects from entering the human body.

Learning Objectives: Students will:
predict what will appear on “sticky cards”
observe how a sticky surface attracts airborne debris using petroleum jelly and pepper 
infer that sticky substances in the respiratory system help trap germs and prevent them from entering the human body.
record predictions, observations and conclusions relating to activity in journals.

NJ Science Standards: The purpose of this lesson is to help students see how the respiratory system helps protect the human body from germs and other airborne objects.  This connects to Standard 5.1: All students will learn to identify systems of interacting components and understand how their interactions combine to produce the overall behavior of the system.

Materials/Resources:
Germs Makes Me Sick by Melvin Berger and Marilyn Hafner  
12 index cards (6 for demonstration and 6 for exploration)
hole punch
1 jar petroleum jelly 
6 squares waxed paper (12” x 12”)
6 – 2 ft. lengths of yarn
12 –15 hand lenses
6 small plastic cups
pepper
paper towels

http://www.cellsalive.com/index.htm – a website whereby students can view bacteria and viruses

Procedure:
Introduction:
Rather than read the above book, just select portions that describe function of mucus. Click on website for photos of bacteria and viruses.

Have students list things that are sticky.  Record their responses on chart paper. 

Explain that there is a sticky substance that lines the passageways of the nose, mouth, and throat (the respiratory system).  See if they know what the substance is called. Today we are going to find out what that sticky substance called mucus does.  

Exploration:
Spread petroleum jelly on an index card (have five others ready) and give each group a card. Have students make observations about the cards with hand lenses and record their findings in the first box of the lab sheet.  Have students think about and record in the second box predictions of what will happen if the cards are hung in a “windy” spot for two days. Students share predictions. Table captains will get the materials for the next part of the exploration. Each student will feel a small dab of petroleum jelly to wipe their fingers onto an index card and remove the rest of the jelly from their hands with paper towels. They will describe the texture of the jelly. Students (person across from the table captain) will shake the pepper over the index card and tap it on its side (procedure is explained), then record what they see by drawing a picture in their journals. Show the prepared demonstration cards and explain that they have been hanging in a “windy” place for two days. Students will examine the demonstration cards for airborne particles using hand lenses and describe what they see in their journals.

Student Product:
Application:
The teacher will lead a brief question based discussion on how the respiratory system and the lab are related. First we talked about germs, the human body and a sticky substance.  Where was that sticky substance?  What is it called?  Then we did a lab with petroleum jelly, pepper, and dust!  What might one thing have to do with the other?  Talk about it at your tables. Group answers will be shared with the class.

Why do you think we have mucus?  Why does it need to trap dust and germs?  How does it trap dust and germs? One might want to describe the composition of “boogers” as dried mucous and airborne irritants.

Assessment:
Understanding of content and processes will be assessed by direct observation of activity, participation in group discussions, and journal responses. Thinking question: Why do we have more mucous when we are sick? Essay: Is mucus good or bad – explain….

Note: mucus is a noun - mucous is an adjective.

Reflection: This lesson is a follow up of a prior lesson that shows how germs are spread. If a stereomicroscope is available, it is perfect for viewing the particles that are captured on the index cards. One can also hang strips of scotch tape and view what gets “caught” on the strip. The idea is not to frighten children about germs, but to inform them about how they can stay well. Our body has an immune system that fights germs, and we can help by washing our hands, cuts, using Band-Aids, staying home when ill, and not sneezing and spreading mucus in the air and objects near other people by sneezing, coughing and not covering our mouths. Younger students tend to have a wealth of stories about these topics. Viewing the website makes the germs visible!