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4. Critical Thinking, Problem Solving, and Decision Making
 

Students use critical thinking skills to plan and conduct research, manage projects, solve problems, and make informed decisions using appropriate digital tools and resources. Students:
 
a.

identify and define authentic problems and significant questions for investigation.
b. plan and manage activities to develop a solution or complete a project.
c.

collect and analyze data to identify solutions and/or make informed decisions.
d.

use multiple processes and diverse perspectives to explore alternative solutions.


In this lesson plan students will be able to gather bacteria from different areas of the school and grow them on an artificial media. Students will be able use technology for the purposes of research. In the process we will use a incubator, microscopes, and use an excel spreadsheet to organize their data. Students will have to use critical thinking skills to understand that life has certain requirements to survive, and we will try to simulate these conditions. These are authentic problems that we all have to understand. There are bacteria all around us, some are harmful and others are not. It is through this knowledge that people will realize that things like food can harbor harmful pests and must be used cautiously.We will collect and analyze data as individuals then share the information as a group to get a better idea of where most bacteria like to hang out. The final part of this project is to look at alternative methods that will help limit the number of bacteria. through changes in pH, temperature and other means.



Where can we find bacteria?

 

Modified from Liz La Rosa

 

www.middleschoolscience.com

 

 

Objectives:

 

v   To take bacterial swabs from various places in the school.

 

 

v   To inoculate a petri dish with a bacterial culture.

 

 

v   To count bacterial colonies.

 

 

v   To find out where most bacteria hang out.

 

 

v   To determine what kind of environmental conditions influence bacterial growth.

 

 

 

Pare Lab Questions:

 

 

1)    Where do you think you will find the highest amount of bacteria?

 

2)    What do you think the petri dish will look like in 3-4 days?

 

 

 

 

 

 

 

 

 

Materials: (per group of 2 students)

 

v   1- petri dish with agar (Each student uses half of the petri dish)

 

v   2 cotton Q-tips

 

v   Grease pencil

 

v   2 index cards with sample location

 

v   Incubator

 

 

 

Procedure:

 

 

1)    Each group of 2 will share one petri dish.

 

2)    Turn the dish upside down and using your grease pencil, draw a line down the middle of the dish so that you have two equal halves.

 

3)    Place your initials, date and sample location along the bottom perimeter of the dish, NOT in the middle.

 

4)    When you and your partner are ready, come up and get your sterile Q-tip. Be very careful not to touch the side that will collect your sample, your hands can contaminate the Q-tip and alter your results.

 

5)    Find an area to collect your sample like:

 

a.     The bathroom sink

b.    Door handle

c.     Vending Machine

d.    Armpit

e.     Nose

f.      Behind your ear (find out why your parents tell you to clean behind your ear!)

 

6)    Carefully open your petri dish as little as possible (like an alligator opening its mouth --- < ---).

 

7)    Lightly rub your Q-tip across the agar on your side of the dish.

 

8)    Repeat steps 6 and 7 allowing your partner to swab his side.

 

9)    Tape the dish shut, and draw what your dish looks in your lab notebook

 

10) Place your petri dish upside down on the tray in the front of the classroom.

 

11) We will examine the colonies in a few days after they have incubated at around 100⁰Fahrenheit (37⁰Celcuis).

 

 

 

Data:

 

Figure 1 : Draw your petri dish as soon as you have placed your sample on the agar.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 2: Draw you Petri Dish after 3 - 4 days of incubation.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 1: Number of Colonies on petri dish

Location of Sample:

Colony Color:

Colony Color:

Colony Color:

Number of Colonies:

 

 

 

 

 

 

 

 

 

 

 

Analysis:

 

1)    How many clusters (colonies) of bacteria appear to be growing in each petri dish?

 

 

 

2)    Which petri dish had the most growth? The Least?

 

 

 

3)    Why was the agar sterilized before this investigation?

 

 

 

4)    Check out classmates petri dishes and find out where they got samples from. What kind of environmental conditions seem to influence where bacteria are found?

 

 

 

 

5)    How do you think you can control the amount of bacteria that you will encounter? (Hint: Observe plates in front of room with disinfectants).

 

 

 

 

6)    Which method worked best in stopping bacterial growth?

 

 

Conclusion: What did you learn from this experiment? What would you do different next time? (3-5 sentences)

 

 

 

 

 

 

Teacher tips:

 

One the first day swab a number of plates and place small amounts of disinfectants on agar (bleach, tear drops, school soap, salty water, H2O2, etc.) And allow students to observe which disinfectant worked best and which did not work. Notice the "ring of death" around where the disinfectants were placed.

 

Prepare the petri dishes a few days ahead of time. They are time consuming and require sterile procedures. Follow agar directions.

 

Leave one petri dish open on your desk all day long. Explain that there is bacteria floating in the air and landing on the dish RIGHT NOW! Close the dish and place it in a warm place. Show them the dish in a few days and they will be amazed!

 

Discuss the importance of keeping the lids on the petri dish and to only open the dish enough to place the Q-tip in and take out. Use the "Alligator" technique.

 

Make a list of the places that the kids can go to for a sample. Have them pick an index card, at random, and that is where they will get their sample. The index card also acts as a hall pass. Students are allowed a few minutes to go and come back.

 

Some places to go are: water fountain, bathroom toilet handle, door knobs, secretary's phone, nurse's office bed, banisters, gym locker room benches or floors, cafeteria tables, computer keyboards, student desks, etc....

 

Fuzzy Colonies = Fungus not Bacteria

 

When going over the samples, place the all the dishes on a large table and see which areas got the most bacteria.

 

           You may also notice patterns, that certain colony types (same color for example) may be from certain locations.

 

Dispose of the petri dishes carefully! If possible, autoclave them and place them in biohazard bags or multiple bag layers.