Biology Lab Report

Instructions: You will be completing a hands-on laboratory investigation that demonstrates the importance of hand-washing.

Title:

Objective(s):

Hypothesis:

Variables:

Materials: washable paint, warm running water, towel, blindfold, hand soap, timer

Procedures:

Pick one person to be the hand washer and one person to be the timekeeper. You will both have the opportunity to complete each of the experiments, so you will each be washing your hands two times.

For each trial of this experiment, the timekeeper (the partner not washing hands) will be responsible for determining the cleanliness of the washer’s hands at each time interval. Use the following scoring guide as a reference.

Scoring Guide:
Completely Dirty Very Dirty Somewhat Dirty Slightly Dirty Clean
4 3 2 1 0
**Discuss as a team the factors that you will use to determine the level of cleanliness observed at each time interval before you get started.**
Washer #1 should put a small amount (about a tablespoon) of washable paint on the palm of one hand and spread it evenly over both hands. Be sure to cover the backs of the hands and the skin next to and under the fingernails. Allow the paint to dry completely.
Go to the sink and blindfold Washer #1 so he or she can’t see his/her hands. Turn on warm (not scalding hot!) water. Have Washer #1 wash with just water for one second. After one second, have the timekeeper blot dry the washer’s hands by very lightly touching the paper towel to the skin (do not rub!). Use the scoring guide to record the cleanliness on the “water only” data table in the row marked “Washer #1.” Do not let Washer #1 see his/her hands, and be sure that you do not give away any hints about how clean they are.
Have the washer wash for four more seconds with just water. Again, lightly blot the washer’s hands and record their cleanliness in the data table.
Have the washer wash for 15 seconds more with water. Once again, blot and record the cleanliness on the data table.
Take the blindfold off and allow the washer to completely clean his/her hands.
Change roles and repeat steps 2 through 6 with Washer #2. Record these results on the second row of the data table, under “Washer #2.”
Now change roles again so that Washer #1 is back to the role of hand washer. Repeat steps 2 through 6, having the washer use soap each time. Record the results in the appropriate row of the data table.
It is now time for Washer #2 to repeat steps 2 through 6 using soap each time. Record these results in the second row of the data table.
Data and Observations:
For each trial of this experiment, the timekeeper (the partner not washing hands) will be responsible for determining the cleanliness of the washer’s hands at each time interval. Use the following scoring guide as a reference.

Scoring Guide:

Completely Dirty Very Dirty Somewhat Dirty Slightly Dirty Clean
4 3 2 1 0
Data Table:

Use the scoring guide above to record the level of cleanliness at each time interval.

Water Only:

Total wash time (in seconds) 0 seconds 1 second 5 seconds 20 seconds
Washer 1
Washer 2
Average cleanliness score
Soap and Water:

Total wash time (in seconds) 0 seconds 1 second 5 seconds 20 seconds
Washer 1
Washer 2
Average cleanliness score
Data Analysis:
Create two graphs showing the average cleanliness score at each time interval. One graph will show the average results with water only and the other will show the average results for soap and water. Total time washed should go on the horizontal x-axis (marked from 0 to 20 seconds), and the cleanliness rating should go on the vertical y-axis.

Insert chart here.
Conclusion:
Be sure to address all the following points as a summary in the conclusion of your lab report:

Was your hypothesis correct or incorrect? Why or why not?
How do the results of the four trials compare?
What, if any, errors or inconsistencies may have occurred in this experiment?
Based on these results, what is the importance of soap and time for effective hand washing?
What areas of the hands retained the paint the longest, requiring careful scrubbing to get clean?
Analyze the graphs. What do they indicate about the time it may take to effectively wash your hands?
Questions:
Using what you have learned in the lesson and from the experiment, answer the following questions:

What suggestions do you have for improving this lab and minimizing errors or inconsistencies? Be specific.
Describe the various defense mechanisms your body has to fight pathogens, nonspecific and specific. How does not washing your hands properly affect these mechanisms?