Your Body: A Bacteria Incubator!

From WikiEducator
Jump to: navigation, search
Biology in Elementary Schools home

| Instant wiki maker | Making handouts | Editing tips |
SMlogo stacked purple.jpg

Biology In Elementary Schools is a Saint Michael's College student project from a course that ran between 2007 and 2010 and fully described in this book chapter. The student-created resources have been preserved here for posterity. Link under 'toolbox' for printer-friendly versions of the exercises. Click on handouts to print full resolution versions. Please see Wikieducator's disclaimer, our safety statement, and the Creative Commons licensing in English and in legalese.

Your Body: A Bacteria Incubator

Student Worthiness

This experiment has yet to be fully completed by students. We believe that the jello will create an appropriate substance in which to create growth.


This activity involves culturing bacteria and fungi that are in the air and on children's bodies. Although these organisms may seem harmless, they can and do cause infection, particularly when their numbers increase when they are cultured. For that reason it is strongly recommended that the plates never be reopened. Fungi are very likely to grow on gelatin, and the spores may cause allergic reaction or infection. The plates should be sealed tightly; we used high-quality masking tape for that purpose. The used plates should be sealed in a plastic bag prior to appropriate disposal.

Primary biological content area covered

Bacteria Growth & Safe handling of food


  • Unflavored gelatin packets
  • Petri dishes or baby food jars (one for each student)
  • Cotton string
  • Permanent marker
  • Hot water
  • Glue gun with glue sticks
  • Wet wipes
  • Large bowl
  • Spoon for stirring gelatin
  • Masking tape may replace glue for connecting the lids to the bottoms


Handout 1. This handout maps out all the parts of the apple for the students to identify with.
  • Students will be given a chart with two separate columns to make a hypothesis on. The other section of the chart will be used later on in the experiment for the students to record their conclusion.

Lesson plan

Teacher Preparation

  1. Sterilize petri dishes and lids in hot water.
  2. Mix the gelatin with hot water (1 packet gelatin to 2 cups water).
  3. Pour gelatin mixture into petri dishes until each is about half full. We recommend doing this step ahead of time so gelatin can set for experiment day. Put the lids on to prevent skewed results from airborne bacteria.
  4. Place dishes in refrigerator for gelatin to become firm.


  1. Pass out dishes and have children label them with their names. Label one extra petri dish "Control". This dish will be used to compare the grown bacteria dishes to one that has no bacteria in it.
  2. Cut a piece of string for each student. Students will use the string to collect bacteria.
  3. Have students collect bacteria from a place on their bodies (ie. behind ears, between toes, belly button, armpit, etc.).
  4. Then have students place strings into their gelatin-filled petri dishes. It is important to open and close the dish quickly to prevent additional bacteria in the air from entering.
  5. Each student should label their dish with their name, date, and what part of the body they took bacteria from.
  6. With a teacher's assistance, tape the petri dishes closed.
  7. Have students write a hypothesis on the handout provided, as to what will happen over time in the petri dishes.
  8. Speak with students about the bacteria that are on their skin. Discuss anti-bacterial soap and why it may not be beneficial for the human body.
    • -Chemicals, like triclosan, which is in soap, end up killing all susceptible bacteria, some of which are not harmful.
    • -Some antibiotic-resistant bacteria have a chance to multiply, causing harm to the individual.
    • -People must be exposed to some bacteria in order for their immune systems to develop and be strong.
    • -For more information helpful to teachers regarding anti-bacterial soap, see:!
  9. Give petri dishes to teacher so kids can see results and discuss the bacteria in a few days.
  10. Emphasize to teacher and students the importance of keeping the dishes closed and disposing of them properly after the results of the experiment have been viewed.
Example of string in a contaminated petri dish.

Positives/Negatives & Tips for Successful Lesson

  1. Depending on students' prior knowledge, the background information given may need to be covered in more or less detail. Ask students questions to see their level of knowledge and to allow their knowledge to begin teaching their peers.
  2. The end results will not ever be completely accurate in showing only the bacteria from their designated spot, since by distributing the string, bacteria from the teacher's and from the students' hands were passed.
  3. We used flavored gelatin and found that most plates grew spectacular molds. By comparison, nutrient agar plates that we used had lower numbers of fungi and more bacteria.

Math connections

Students may chart their progress and results. Pies and bar graphs can be created to show what percentage of petri dishes showed bacterial growth versus dishes that failed and had no growth in them.

Multi-Media Connection

Show video clip on bacteria to engage students' attention. Teachers may also use an interactive web activity from the American Museum of Natural History. Check out the website at the bottom of this page in the connections for the link. Click on "Bacteria in the Cafeteria" and follow the directions!

Connections to educational standards

  • S 1-2: 2

Students demonstrate their understanding of PREDICTING AND HYPOTHESIZING by… ∙ Predicting a logical outcome to a situation, using prior knowledge, experience and/or evidence. AND ∙ Explaining reasons for that prediction.

  • S1:2:4 Students demonstrate their ability to CONDUCT EXPERIMENTS by…

∙ Referring to and following a simple plan for an investigation.

  • S3-4:36

Students demonstrate their understanding of Equilibrium in an Ecosystem by… ∙ Explaining how one organism depends upon another organism to survive.

  • S1-2:42

Students demonstrate their understanding of the Patterns of Human Health/Disease.

Next steps

  • Try same activity with other things that may grow bacteria, such as different types of food. Have students hypothesize which materials will grow the most bacteria.
  • Have students perform a play or dance, showing how bacteria grows.

Citations and links

Idea taken from:

Interactive Bacteria Activity:

Vermont State Grade Expectations can be found at the State of Vermont Department of Education website. [1]