Scientific Method 

• State the problem (question)

• Research  (learn about the topic)

• Hypothesis (what you think or believe will happen)

• Experiment (how you test your hypothesis)

• Data (information you learned when you did the experiment

• Conclusion (what you found out from your experiment and data)

State the problem

Which cleans hands better, hand sanitizer or hand soap?

Research

Sarah learned that bacteria are living organisims and the alcohol in hand sanitizer is toxic to them.  Hand soap can kill bacteria if the soap is present long enough to raise the pH high enough.

Hypothesis 

Sarah believed that hand sanitizer would kill more bacteria than hand soap.  

Experiment 

• Sarah had 6 test subjects.  She put a bacteria on every subjects' hands. 

• She swabbed everyone's hands before they put on the hand sanitizer and wash their hands.  

• She put hand sanitizer  on 3 test subjects and 3 test subjects would wash their hands.  

• She swabbed all the test subjects after they washed hands or put on hand sanitizer.  She tested the pH of the hands that were washed in soap to see if the pH went up.  

Data 

• Sarah found that hand sanitizer killed 99% of bacteria while soap only killed 84% of bacteria.  

• The longer the hands were washed in soap, the higher the pH went and the more bacteria was killed.  

Conclusion

Sarah found that hand soap slowly raises the pH of the hand.  If left on for 20 seconds most bacteria was killed.  Hand sanitizer kills more bacteria than hand soap.  Sarah wants to further test different types of hand soap in order to compare them.