Bell Work

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

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

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

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

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

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?

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

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

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

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

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

Background One study found that the Average hand washing time is 6 seconds (http://www.cbsnews.com/news/95-percent-of-people-wash-their-hands-improperly-are-you-one-of-them/) Cdc recommends at least 20 seconds (https://www.cdc.gov/handwashing/) Antibacterial components must remain on a surface for at least 2 minutes for them to work (https://www.ncbi.nlm.nih.gov/pubmed/22300895)

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

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. (https://www.cdc.gov/handwashing/show-me-the-science-hand-sanitizer.html)

Hypothesis Write your group’s hypothesis

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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