1. Bell Work

2. objectives
Compare the effects of different products that claim to kill bacteria
Design a controlled experiment
Plan a methodology using appropriate tools to gather precise and accurate data
Determine if data obtained was valid and reliable
Compose and defend a conclusion based on data obtained from a controlled experiment
Publish results of a controlled experiment
Learn sterile handling techniques for bacteria growth
Successful cultivation of bacteria

3. Testing the effects of various hand cleaners on the growth of E. coli
Pam Stewart

4. Design a controlled experiment
Independent variable
Dependent variable
The types of hand cleaner
The growth of E. coli – determined by measuring the zone of inhibition around each product disk

5. Previous Learning
Students will apply previous learning to design and complete the experiment
Scientific Method
Graphing

6. Journaling for a lab
Research question / Purpose
Background
Independent variable
Dependent Variable
Hypothesis
Create the following sections w/ notes for tomorrow’s lab:

7. Observation
You just left your best friend’s house. (s)he felt fine while you were there but started feeling sick after you left.
You find out that (s)he tested positive for Strep throat.
How can you ensure that you don’t get it too?

8. Wash your hands
You’ve been told many times that the best way to prevent spreading disease is to wash your hands.

9. What works best?
Will regular soap work?
Or should you buy antibacterial?
Or is hand sanitizer best?

10. Research Question Research Purpose
Which product is best for killing bacteria on hands?
Determine which hand cleaner best eliminates bacteria.
Research Purpose

11. background
E. coli is most commonly found in the intestines of humans and other warm- blooded animals
Transmitted easily due to unwashed or improperly washed hands after using the restroom
Prokaryote: one-celled organism w/ no nucleus

12. Background research
Observing one isolated bacterial specimen not contaminated with other microorganisms is not representative of the real world

13. Background
One study found that the Average hand washing time is 6 seconds (
Cdc recommends at least 20 seconds (
Antibacterial components must remain on a surface for at least 2 minutes for them to work (

14. Antibacterial soap (usually w/ triclosan)
Background
Regular Soap
There is a common misconception that antibacterial soap, in particular, is effective in eradicating all germs. Although antibacterial soap may kill some bacteria, it is no more effective in doing so than regular soap, and does nothing to fight viruses like colds or the flu.
Antibacterial soap (usually w/ triclosan)
Must remain in contact with a surface for 2 minutes for antibacterial products to work. Average handwashing time is 6 seconds. Cleans no better than regular soap but Triclosan been found to be disruptive to human endocrine system

15. Background
Although alcohol-based hand sanitizers can inactivate many types of microbes very effectively when used correctly 1-10, people may not use a large enough volume of the sanitizers or may wipe it off before it has dried 10. Furthermore, soap and water are more effective than hand sanitizers at removing or inactivating certain kinds of germs. (

16. Hypothesis
Write your group’s hypothesis

17. What does e. coli look like growing on nutrient agar?

18. What will it look like if the product is effective?
Zone of Inhibition

19. Control Group
We must have a control
How will we make one?

20. Constants / Controlled variables
What do we need to keep consistent to prevent confounding variables?
Type of agar
Same strain of E. coli
Test same products
Same growth time
Same methodology

21. Create your procedures and data table
Disc 1 – water
Disc 2 – antibacterial soap
Disc 3 – regular soap
Disc 4 - hand sanitizer

22. Day 2 – Lab day bell work Prepare yourselves to conduct a lab
Hair pulled back
No loose or dangling clothing / jewelry
Pants
Closed toe shoes
Choose lab group roles

23. objectives
Compare the effects of different products that claim to kill bacteria
Design a controlled experiment
Plan a methodology using appropriate tools to gather precise and accurate data
Determine if data obtained was valid and reliable
Compose and defend a conclusion based on data obtained from a controlled experiment
Publish results of a controlled experiment
Learn sterile handling techniques for bacteria growth
Successful cultivation of bacteria

24. Materials Manager: 1 – agar plate 1 – disposable pipet
1 – sterile swab
1 – paper towel
1 – small petri dish full of paper disks (to soak w/ products)
1 – disinfecting wipe (to clean lab table)
1 – forceps
1 - sharpie

25. Lab Technician Get on a pair of gloves *
Obtain 1 – small yellow tube (E. coli)
* Only the lab tech needs to wear gloves

26. Always label an agar plate on the bottom of the plate!
Recorder - procedures
Always label an agar plate on the bottom of the plate!
Label the plate with your lab group’s period number and lab table number
Example: period 1, lab table 3 = 1 – 3

27. Recorder - procedures 1
Draw 4 small circles, evenly spaced and label them with a number (1 – 4) 4 2 3

28. Everyone - procedures
Create a drawing in your lab book to represent your agar plate and label the circles the same as you did on the plate
Create a key for the disc numbers:
Disc 1 – water
Disc 2 – antibacterial soap
Disc 3 – regular soap
Disc 4 - hand sanitizer

29. Quality Control - Procedures
Today’s goal is to avoid contamination!
Sanitize work station before and after lab
Only open the agar plate lid & yellow tube lid enough to do the required procedures, then immediately close it back
Do not place agar plate lid onto desktop = contamination
Dispose of pipet and swabs in the green bucket on front lab desk

30. Lab Tech - procedures
Using sterile pipet, transfer .25 mL from the E.coli broth tube onto the agar plate
Using sterile swab, spread e. coli broth evenly onto the plate surface
Do this gently so you do not to puncture the agar surface

31. Lab Tech - procedures
Using forceps, dip one piece of hole-punched paper into the product solutions being tested
Do not place the paper over the agar until it has stopped dripping
Dripping the product onto the agar will skew the results!
Using forceps, Place the product soaked paper onto the designated circle on the agar
Repeat for all products being tested

32. Quality control - procedures
Allow 5 minutes for everything to soak into the agar
Turn agar plate upside down, then place it into the incubator
The lid should be on the bottom at this point
recorder
Record the temperature on the incubator
Everyone
Clean and sanitize work station

33. Everyone
Create a data table to use to measure your results tomorrow.

34. Get out your notebooks for the lab
Bell Work – Day 3
Get out your notebooks for the lab
Turn in your article assignment

35. objectives
Compare the effects of different products that claim to kill bacteria
Design a controlled experiment
Plan a methodology using appropriate tools to gather precise and accurate data
Determine if data obtained was valid and reliable
Compose and defend a conclusion based on data obtained from a controlled experiment
Publish results of a controlled experiment
Learn sterile handling techniques for bacteria growth
Successful cultivation of bacteria

36. Lab Tech
Obtain your group’s plate from the incubator
Do not open it!

37. results
Decide with your lab group if you will measure the radius or the diameter
Measure the zones for each product
You must measure in mm
Inches = 2.54 cm
2.54 cm = 25.4 mm
Share results with teacher to add to class data

38. Bell Work – Day 4 What is bias in an experiment?
Pick up your graded work on the front desk

39. Assignments
These videos are linked under the daily agenda and under the assignments page

40. objectives
Compare the effects of different products that claim to kill bacteria
Design a controlled experiment
Plan a methodology using appropriate tools to gather precise and accurate data
Determine if data obtained was valid and reliable
Compose and defend a conclusion based on data obtained from a controlled experiment
Publish results of a controlled experiment
Learn sterile handling techniques for bacteria growth
Successful cultivation of bacteria

41. Class Results What can we determine based on these results?
Did we support or reject your hypothesis?

42. Graphing the results Conclusions
Working with your table group, put the class data into graph format.
Conclusions
Using the class data, analyze whether the results obtained support or reject the hypothesis for your group.
What did data clearly show?
Potential sources of error

43. Publishing the results
Each group will create a lab report that contains the following information:
Research purpose or research question
Hypothesis
1 or 2 sentence methodology summary
Graph of results
Conclusion statement - Should include an overall statement of most effective product and how that relates back to hypothesis
Acknowledge any potential errors &/or necessary improvements

44. Exit ticket
Did this experiment have any confounding variables? If so, what were they?