MC	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

The 6^th grade students were each given an assignment to prepare an experiment on microorganisms at home that they could share with the class. Part of their assignment was to write about their experiment and what they learned about microorganisms from doing this experiment. Here are a few examples:

1. Mary grew mold on potato slices in four different temperatures. She carefully recorded her data, took pictures of the growth, and wrote a complete conclusion.

2. Scott grew fungi on bread; he tested the effects of the amount of moisture on the growth of fungi. He explained to the class what he had learned with the help of a graph.

3. Leslie wanted to test different foods to see which one would grow fungi best. She wrote a hypothesis before she started. She carefully monitored her project and recorded the data. She understood and explained to the class which food had worked best.

4. Candace wanted her project to test whether fungi would grow better in a dark area, or in a light area. She wrote a problem, did research, wrote a hypothesis, wrote her procedure, kept data, and wrote a conclusion.

Which student experiment is valid?

a. #1-Mary recorded data, took pictures and wrote a conclusion

b. #2-Scott experimented, and created a graph

c. #4-Candace, she used the scientific method.

d. All of the experiments used appropriate scientific investigations.

Correct Answer: d

MC	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

Which of these questions can be answered by only making observations (i.e. without planning and conducting an experiment)?

a. What is the effect of sugar on the growth of yeast?

b. How does temperature affect the growth of bread mold?

c. Does antibacterial soap really affect the growth of bacteria?

d. What are three ways that protozoa move?

Correct Answer: d

MC	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

Which of these science questions could NOT be tested with an experiment?

a. What is the effect of light on the growth of bread mold?

b. What brand of home insulation works best?

c. What is the best kind of algae to grow?

d. What brand of light bulb lasts the longest?

Correct Answer: c

MC	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

A scientist wonders if a certain bacteria can survive being frozen. Which of the following is a correctly written hypothesis?

a. If bacteria are frozen, they will die.

b. Bacteria are small, microscopic life forms.

c. The bacteria died when it was frozen.

d. Bacteria survive best when they are moist.

Correct Answer: a

MC	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

The assignment at the end of the unit on microorganisms was for each class group to investigate a microorganism of their choice.

Group 1 chose to investigate the effect of media (food source) on bacteria population growth. They exposed comparable cultures of a given species of bacteria to three kinds of media. Then, they observed and recorded the growth of the colonies.

Group 2 decided to investigate what kinds of algae and protozoa lived in the stream behind the school. They collected water samples, examined them under a microscope, and then drew illustrations in their journals of what they found.

Group 3 chose to investigate the effect of fertilizer on the protist Euglena. They put 10ml of a Euglena culture into each of 10 flasks containing 100ml of distilled water.

Group 4 wanted to investigate what kind of microorganisms were in the air of the classroom. They exposed 10 agar Petri plates to room air for 5 minutes, closed and sealed them. Then every day for 10 days they observed and recorded what grew.

Use your understanding of the nature of science to select the correct answer.

a. Groups 1 and 3 are the only examples of Ògood scienceÓ because these groups set up an experimental design using the scientific method.

b. All of the groups are examples of Ògood scienceÓ because their findings are based upon evidence.

c. Groups 1 and 3 are not examples of Ògood scienceÓ because the answers to their investigations could already be found in books, journals, or on-line.

d. None of these investigations are examples of Ògood scienceÓ because they were not performed by professional scientists.

Correct Answer: b

I	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

The foods listed on this data table were left in plastic bags in a warm container for 5 days. Observations were made and recorded at the end of the experiment. Use this information to answer the next 4 questions.

Food	Observations after 5 Days
Bread	Covered with black, fuzzy mold
Banana	Slimy, black, turning to liquid
Hamburger	Turned brown, smelly
Cheese	Has white and green coating

1. Which of these hypotheses might have been tested in this experiment?

a. Foods left in the dark will rot differently than foods in light.

b. Will foods react differently to plastic bags?

c. If different foods are decayed, they will not decay the same.

d. What kind of bacteria is best for making cheese?

2. What variable was tested in this experiment?

a. The length of time it takes for food to rot.

b. What kind of bags allows rotting to occur?

c. The temperature microorganisms like best.

d. How different kinds of food rot.

3. Which of the following is a conclusion you could make concerning this data?

a. All foods rot when left in a warm place for 5 days.

b. Bread is better for you to eat than cheese.

c. Different microorganisms prefer different kinds of food.

d. Meat is less safe to eat than other foods because it smells bad.

4. How might a student improve this experiment?

a. Count the number of microorganisms on each food with a toothpick.

b. Use a microscope to identify the kinds of microorganisms.

c. Add some strong chemicals and see what they do to the foods.

d. Kill the microorganisms and make the food safe.

Correct Answers:

1. c

2. d

3. c

4. b

I	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

Sarah designed and performed an experiment to investigate the growth of bacteria on a food source. This is the graph of her data.

1. Explain how the bacterial population (numbers) changed through time.

2. What might have caused the change in numbers from b to c?

Correct Answers:

1. (a) The bacterial population increased for the first 10 hours. (b) Then it stayed the same for two hours. (c) For the next 4 hours, the population went down.

2. Maybe the bacteria used up the food source. Maybe the waste materials from the rapid growth in bacteria slowed down the growth and killed other bacteria. Maybe the food source dried out.

I	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

Caleb designed and performed an experiment to test how well different disinfectants work. Here is a table of his data.

Disinfectant	Average Surface Area of Bacteria Colonies (in square centimeters)
A	0.5
B	1.0
C	5.0
D	2.5
E	3.0

1. Create a graph that displays CalebÕs data.

2. Which disinfectant was best at killing bacteria? Explain your answer.

Correct Answers:

1. Sample Graph:

2. Disinfectant A because according to the data A had the least growth and therefore had killed the most at the beginning of the experiment.

I	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

Arturo treated two slices of bread with a bread mold culture and placed the bread in plastic bags. He then placed one bag in a refrigerator and one slice on the teacherÕs desk. One week later, he observed much more mold growing on the bread on the teacherÕs desk than the one in the refrigerator. Which of these is a good science conclusion based on ArturoÕs data?

a. More mold grew on the bread on the teacherÕs desk because it was in the light.

b. Less mold grew on the refrigerated bread because it was in the dark.

c. Less mold grew on the refrigerator bread because the temperature was lower.

d. He cannot make a good science conclusion because he tested two variables at once, temperature and light.

Correct Answer: d

E	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

Ben notices the milk he poured on his breakfast cereal is lumpy and tastes sour. What inference should Ben make?

Correct Answer:

The milk is old or has been left in a warm place.

E	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

Write a possible hypothesis for each of the following questions.

1. Does light affect the growth of yeast?

2. Does ultraviolet light affect the growth of mold on bread?

3. Is antibacterial hand soap better than regular hand soap in killing bacteria?

Possible Answers:

1. If a yeast culture is exposed to light, then growth will increase (also decrease, not be affected).

2. If bread mold is exposed to ultraviolet light, then growth will decrease (also increase, not be affected)

3. If bacteria are treated with antibacterial versus regular hand soap, then there will be no difference in the growth of bacteria (also increase, decrease)

E	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

Katie wishes to see if apples will keep and not rot if they are kept cold. She places an apple in the refrigerator and records the date. What should she use as a control?

Correct Answer:

Another apple should be placed in a warm place the same length of time.

E	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

A group of students wonders if pond water smells bad because it has microorganisms in it. Describe a way they could find out.

Correct Answer:

Use a microscope and look at the pond water to see if microorganisms are visible then boil the pond water to kill microorganisms and see if it still smells.

E	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

The 6^th grade students were each given an assignment to prepare an experiment on microorganisms at home that they could share with the class. Part of their assignment was to write about their experiment and what they learned about microorganisms from doing this experiment. Here are a few examples:

1. Mary grew mold on potato slices in four different temperatures. She carefully recorded her data, took pictures of the growth, and wrote a complete conclusion.

2. Scott grew fungi on bread; he tested the effects of the amount of moisture on the growth of fungi. He thoughtfully explained to the class what he had learned.

3. Leslie wanted to test different foods to see which one would grow fungi best. She wrote a hypothesis before she started. She carefully monitored her project and recorded the data. She understood and explained to the class which food had worked best.

4. Candace wanted her project to test whether fungi would grow better in a dark area, or in a light area. She wrote a problem, did research, wrote a hypothesis, wrote her procedure, kept data, and wrote a conclusion.

The teacher graded all the projects equally. Candace was upset; she felt that she was the only one that deserved an A, because she was the only student who had used the Scientific Method correctly.

What do you think? Does the Scientific Method always have to be used in science investigations? Defend your answer with at least two supporting sentences.

Correct Answer:

(Give points for any of these ideas.)

Science investigations can be done with a variety of methods. The scientific method is only one way. It can be modified to better fit your experiment. There are many different procedures you can use. It is better to use several different methods of discovering, experimenting, and investigating.

P	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

Devise an experiment that would test the hypothesis that warmth will cause milk to spoil. Identify your research question, controls and variables used, and be sure your analysis and conclusions reflect the results of your experiment.

Write a report of your experiment. Your report will be scored on all of the following six qualities.

a. components of the report

b. question/purpose

c. procedures

d. data

e. conclusion

f. spelling, punctuation, grammar

Scoring Guide:

	4	3	2	1
Components of the report	All required elements are present and additional elements that add to the report (e.g., thoughtful comments, graphics) have been added.	All required elements are present.	One required element is missing, but additional elements that add to the report (e.g., thoughtful comments, graphics) have been added.	Several required elements are missing.
Question/ Purpose	The purpose f the lab or the question to be answered during the lab is clearly identified and stated.	The purpose of the lab or the question to be answered during the lab is identified, but is stated in a somewhat unclear manner.	The purpose of the lab or the question to be answered during the lab is partially identified, and is stated in a somewhat unclear manner.	The purpose of the lab or the question to be answered during the lab is erroneous or irrelevant.
Procedures	Procedures are listed in clear steps. Each step is numbered and is a complete sentence.	Procedures are listed in logical order, but steps are not numbered and/or are not complete sentences.	Procedures are listed but are not in a logical order or are difficult to follow.	Procedures do not accurately list the steps of the experiment.
Data	Professional looking and accurate representation of the data in tables and/or graphs. Graphs and tables are labeled and titled.	Accurate representation of the data in tables and/or graphs. Graphs and tables are labeled and titled.	Accurate representation of the data in written form, but no graphs or tables are presented.	Data are not shown OR are inaccurate.
Conclusion	Conclusion includes whether the findings supported the hypothesis, possible sources of error, and what was learned from the experiment.	Conclusion includes whether the findings supported the hypothesis and what was learned from the experiment.	Conclusion includes what was learned from the experiment.	No conclusion was included in the report OR shows little effort and reflection.
Spelling, Punctuation, Grammar	One or fewer errors in spelling, punctuation, and grammar in the report.	Two or three errors in spelling, punctuation, and grammar in the report.	Four errors in spelling, punctuation, and grammar in the report.	More than four errors in spelling, punctuation, and grammar in the report.

P	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

When Joseph poured milk on his breakfast cereal, the milk was sour and lumpy. He checked the date on the bottle and found that the freshness date had not expired. He felt the bottle and it was warm. He wondered if someone had left it out.

What had caused the milk to sour?

Develop a hypothesis explaining why the milk was sour.

Using the format below, write an experiment to test your hypothesis.

Conduct the experiment with help from your teacher.

Problem: Why did the milk sour before its freshness date expired?

Hypothesis: (What do you think happened?)

Procedure: (How are you going to test it?)

Data: (What happened?)

Conclusion: (Was your hypothesis correct? What did you learn?)

Scoring Guide:

	3	2	0
Hypothesis	Correctly stated using an ÒIf-ThenÓ statement.	Shows limited understanding of a hypothesis, no ÒIf-ThenÓ statement.	Statement is not a hypothesis.
Procedures	Procedures are listed in clear steps. Each step is numbered and is a complete sentence.	Procedures are listed in a logical order, but steps are not numbered and/or are not in complete sentences.	Procedures are listed but are not in a logical order and some steps are missing.
Data	Easily followed containing all procedural steps in their correct order.	Complete, but directions are confusing and hard to follow.	Incomplete, lacking data, a title. Hard to follow.
Conclusion	Conclusion includes whether the findings supported the hypothesis, and what was learned from the experiment.	Conclusion includes whether the findings supported the hypothesis, but does not state what was learned.	Conclusion is incomplete and confusing.
Teacher observation	Student stayed on task. Completed the assignment within the guidelines. Project is neatly done.	Student struggled with completing the task on time. Project is hard to read.	Project is incomplete and sloppy.

P	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO:

YEAST GROWTH

Given the following research question, select a variable and then plan an experiment to answer your question.

Question: How does (variable) affect the growth of yeast?

(Remember: Growth/Reproduction in yeast can be measured by the amount of gas produced.)

---

Question (underline variable to be tested):

__________________________________________________________________

Hypothesis (in ÒIfÉ, thenÉÓ form):

_________________________________________________________________

Manipulated (Independent) variable: ________________________________

Responding (Dependent) variable: __________________________________

Procedure (numbered in sequence):

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Materials list (items and quantities):

___________________________________ _________________________________

___________________________________ _________________________________

___________________________________ _________________________________

Sample Answer:

Question: How does salt affect the growth of yeast?

Hypothesis: If salt is added to a yeast culture, then yeast growth will increase.

Manipulated (independent) variable: salt

Responding (dependent) variable: growth of yeast

Procedure:

1. Place 4 ml of yeast in each of 10 clean, identical narrow-mouthed containers.

2. Add 4 ml of sugar to each container.

3. Add 2 ml of salt to each of 5 of the containers.

4. Add 75 ml of warm water to each container and swirl each 10 times to mix.

5. Cover the mouth of each container with a balloon.

6. Observe and compare the amount of gas produced in each container. To measure the volume of each balloon pinch off the balloon with your fingers and lower into a graduated container of water. Record the amount of water displaced.

Materials list:

10 narrow-mouthed containers (>100 ml)

Yeast (~40 ml)

Sugar (~40 ml)

Salt (~ 20 ml)

Warm water (~750 ml)

Graduated cylinders

ml measure

10 balloons

Flask of water with ml scale

P	6^th Grade	Standard: 05
Objective: 02. Demonstrate the skills needed to plan and conduct an experiment to determine a microorganismÕs requirements in a specific environment.
ILO: