Beacon Lesson Plan Library
Can Bacteria Arise from Non-living Things?
DescriptionThis lesson is a lab activity in which students work in groups to solve the problem, 'Can bacteria arise from non-living things?'
ObjectivesThe student knows that investigations are conducted to explore new phenomena, to check on previous results, to test how well a theory predicts, and to compare different theories.
MaterialsMaterials (per group):
- 1 compound microscope
- 6 microscope slides & 6 coverslips
- 6 droppers
- 6 test tubes
- 2 solid rubber stoppers, to fit the test tube
- 1 rubber stopper, to fit the test tube with a straight glass tubing
- 1 cotton plug with an 'S'-shaped glass tubing
- 1 test-tube rack
- 1 hot plate
- 1 timing device (a watch with a second hand will suffice)
- 1 1000-mL beaker
- 1 10-mL graduated cylinder
- 1 100 mL graduated cylinder
- Beef broth or nutrient broth
- 1 permanent marker (any color)
- 1 labeling tape
- Lab instruction sheet
Preparations1. Assemble all lab materials.
2. Prepare copies of lab/data table sheets.
3. Purchase graph paper. (One sheet for each student or one sheet for each group of students.)
4. Emphasize safety procedures with your class before this or any lab activity.
1. Begin the lesson with an introduction similar to the following:
For hundreds of years, people believed that living things could arise spontaneously from non-living things. They believed that spontaneous generation, also known as biogenesis, produced the bacteria found in broth exposed to air. The bacteria supposedly came from broth in the presence of some special ingredient in the air. This idea was disproved by the French chemist, Louis Pasteur.
Pasteur hypothesized that living things could only come from other living things. This idea is known as biogenesis.
2. Divide your class into groups containing four students each.
3. Distribute the experiment activity sheets, one per student.
4. Give a brief explanation of the activity so the students know what they are to accomplish during the lab experiment.
5. Walk around the classroom and make sure every group is performing the lab properly.
6. Allow the students to work in their groups until there are 5 minutes left in the class period.
7. Tell the students to place their lab equipment and the reaction vessels on a table or cart so that the reaction vessels will be undisturbed until the class meets again the next day.
1. Tell the students to retrieve their lab group's reaction vessels for the observation and conclusion portion of the lab activity.
2. Tell the students to follow the lab activity sheet's instructions for observing the bacteria growth in the test tubes and for preparing the microscope slides.
3. Check all lab groups to see that they are performing the activity correctly, i.e. preparing of the wet slides and microscope use.
1. Tell the students to record their observations for each test tube in their data table; T for turbidity, C for clear,TTfor high level of turbidity.
2. Tell the students to record their observations for each slide; B for presence of bacteria, A for absence of bacteria, and BB for high numbers of bacteria.
1. Tell the students to brainstorm together to determine the relationship between the rate of bacterial growth and the absence or the presence of air and/or heat.
AssessmentsAssess a completed lab sheet from each student that includes the data collected from the activity, a graph of the results and a summary of the data and the contributions to the conclusions drawn.
Attached FilesA lab activity sheet, data collection table and conclusion statement. File Extension: pdf
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