Summer Research Program for Science Teachers





Shereen Springer

Erasmus Hall: Campus School of Humanities, Brooklyn

August 2003



How do white blood cells fight foreign organisms that invade our body?




Grade Level: 9th


Time Allocation: 45 minutes



Instructional Objectives: 

At the end of this lesson, students should be able to:

            ·Describe the function of white blood cells.

            ·Name the major types of white blood cells.

            ·Explain how white blood cells destroy invaders.

            ·Describe the process of phagocytosis.



1.      Computers with Internet access.

2.      Student work sheet

3.      Power-point software


Do Now/Motivation:

1.      What would you do if you found strange, uninvited people in your home in the middle of the night?


2.      Very young babies often get high fevers, but as they get older, the frequency of the fevers decreases.  Why do you think they get fevers so often?

Why do the fevers become less frequent as the baby gets older?



            The immune system, which responds to an invading pathogen, is an intricate system of defense mechanisms designed to block and destroy any foreign substance entering the body.  It is made up of many cells, which help it to perform its function.  One of the major types of cells is white blood cells.  White blood cells are responsible for the defense system in the body.  There are approximately ˝ a million white blood cells in every drop of human blood.  White blood cells fight infections, and protect our body from foreign particles, which includes harmful germs, and bacteria.  White blood cells, like red blood cells are formed from the stem cells of the bone marrow. 




            Have students look at the 510k time –lapse movie at , which shows a macrophage engulfing cells of fungus Candida albicans.  Then elicit from the students an explanation of what is occurring in the movie.

1)      Are any of the cells changing shape and why?

2)      Once the fungus gets into the macrophage (white blood cell), how do you think it will kill the fungus?


Emphasize to the students that this process is called phagocytosis, and it is the way in which macrophages, a specific type of white blood cells get rid of pathogens.  The prefix phago means eating, and the suffix cyte means cells.  Thus, a phagocyte is an eating cell.



Internet Activity:

          In this activity, students should work in pairs.  However, each student must complete his/her own worksheet.  Working in pairs allows students to share ideas, and navigate their way through the web much easier.  Have students use one computer per pair.  Have students go to and answer all the questions on the work sheet.


Summary and Application:

            Without the white blood cells, the immune system would not be able to perform its function.  Once the immune system fails to work properly, there is a disruption in the body’s ability to maintain homeostasis.  This disruption will eventually cause diseases.  The breakdown of the immune system in people with HIV/AIDS leaves them susceptible to all types of diseases since the immune system is no longer able to fight off foreign organisms.

Knowledge of the function of white blood cells, and the immune system has led to doctors successfully transplanting organs from one organism to another without rejection.  After the transplant, drugs are administered to suppress the action of the white blood cells, thus preventing them from attacking the foreign organ.


This lesson plan aligns with New York City performance standards: S5b, S5f, S6a, S6d, S7a and S7d.


Return to Biology Lesson Plan Menu