Rotten But Not Forgotten

Lesson Overview:

National Science Education Standards:

Content Standard F: Science in Personal and Social Perspectives
Population, Resources, and Environments

Strand 2: Knowledge of Environmental Processes and Systems
2.1: The Earth as Physical System

Key Concepts:

1. The process of decomposition involves changes in matter.

2. Microbes can be cultured in large quantities.

3. Bioremediation can greatly increase decomposition rates of organic matter and assist in removing contaminants from water and soil.

Objectives:

Students will:

design and conduct investigations to identify the effect bacteria and enzymes have on food samples.

make observations during their investigations, keep accurate records, and report findings.

use graphic representations of data collected during the investigations.

Cross-Curricular Connections:

Language Arts:
• Record and organize information, discuss experimental design and share results.

Mathematics:
• Construct graphs and other representations of data collected during investigations.

Social Studies:
• Discuss how the process of decomposition can be greatly enhanced through bioremediation.
• Investigate various real world applications for bioremediation.

Observing
Communicating
Comparing
Investigating
Inferring
Applying

Materials:

Per Student
• Research Journals
Per Group
• Goggles
• Gloves
• 4-6 quart-sized freezer baggies
• Lab tray or shoebox (something to hold the baggies intact without disturbing them)
• 1-2 slices of bread (other types of organic material may be used, but bread provides a highly visible example of the effects within a few hours)
• RID-X Septic System Treatment, 16 oz (available in grocery/hardware stores. Costs approximately $5.00.) RID-X must be dissolved in water to activate microbial action. Suggested minimal amount to get results within a short period of time: 1 tablespoon per cup of water) aquarium dechlorinator (use as directed, removes chlorine which may adversely affect microbial action.)
• Water
• Spoon
• Measurement tools
• Hand lenses
• Microscopes
• Chart paper
• Markers

One introductory class period and one final class period, with daily 5 minute observations/recordings in between. Observable changes will be noticeable within a few hours, and dramatic change is observable after 24 hours, allowing the lesson to be completed in 2-3 days. (In experiments using ¼ piece of whole wheat bread and 1 cup of water per baggie, with varying amounts of RID-X added initially to warm water and then kept at 80°F (no RID-X, ½ tablespoon RID-X, 1 tablespoon RID-X, 2 tablespoons RID-X), after 24 hours the bread was simply waterlogged in the baggie without RID-X, but there was progressive evidence of decomposition in the RID-X baggies, with the greater amount of RID-X added showing the greater rate of decomposition.)

Procedure:

1. Describe the purpose of the investigation; (1) to determine the effect, if any, that bacteria and enzymes have on the rate of decomposition and (2) determine conditions that inhibit or enhance the rate of decomposition. Elicit student input in designing investigations. Discuss the need for controls and variables to provide accurate information. Variables may include differences in temperature, amount of RID-X, amount of water, exposure to sunlight, exposure to air, etc.
   
2. After listing the possible categories of designs, each group chooses one variable to investigate to ensure that there is variety, and designs the investigation accordingly. Prior to preparing the baggies, review their designs to provide an embedded assessment of their knowledge of experimental design and to allow for the possible redirection of their efforts.
   
3. Students predict and record what will happen to the bread in each baggie, and then prepare their baggies.
   
4. Students follow their procedures, observe the baggies and record observations in their journals over a specified period of time.
   
5. Students analyze their data, graphically represent their findings, and present the information to the class.
   
6. Use the students' information to lead the discussion and bring closure to the activity. Develop the concept of bioremediation and its real world applications (see Suggested Discussion Questions below).
   
7. Properly dispose of experimental materials.

Suggested Discussion Questions:

What changes were observed during the investigation?

Why do you think these changes occurred?

Were there any differences in the decomposition rates of the bread exposed to RID-X, and bread that was placed in plain water?

What were the variables and how did they effect the decomposition rate?

What are the benefits/risks to using bioremediation processes to clean up contaminants in water or soil?

Do you think there may have been a better way to design the investigation?

What would you have done differently?

How does this investigation relate to you in your life?

Do you have a septic tank? Do you believe using a product like RID-X may have some beneficial effects on the microbial action in the septic tank?

Further Investigations:

Interview the city wastewater treatment manager to determine if the city adds microbes in their water treatment process.

Research benefits and risks of using bioremediation.

Contact local industries to determine if they use microbes or plan to in the future.

Locate additional information about bioremediation on the Internet.

Contact local environmental agencies/universities for information on bioremediation and their recommended uses of the technology.

Debate the pros and cons of genetic engineering to enhance the bioremediation process.

Environmental Engineer
Waste Management Engineer
Chemical Engineer
Biologist
Biotechnology Researcher
Quality Control Analyst
Biostatistician
Clinical Data Programmer
Patent Agent

Assessment Procedures:

Investigations should be monitored and judged according to a rubric produced, in part, with student input.

Have students individually design an investigation that would answer a question posed during the investigation to determine if they understand experimental design.