Question

data analysis

1. write a sentence that explains how soap affects the surface tension of water based on the results of your experiment.
2. identify the independent (manipulated) variable and the dependent (responding) variable in your penny experiment.
3. what was the control in the penny experiment? what is the purpose of this control?
4. what other questions can you develop (and even test) about surface tension. write at least two follow - up questions that could be tested using the penny technique.
5. consider the experimental question and how it relates to a water strider. what happens to water striders on lakes that have been contaminated with soap? make a claim to answer this question and support your claim with evidence from the experiment you conducted.

claim
evidence

Explanation:

Step1: Identify variables

The independent variable is what is changed in an experiment. Here, it is the type of water (soapy water or tap - water). The dependent variable is what is measured. Here, it is the number of drops that can fit on a penny.

Step2: Determine control

The control in the penny experiment is tap - water. The purpose of the control is to provide a standard for comparison to see the effect of the independent variable (soapy water).

Step3: Generate follow - up questions

1. How does the concentration of soap in soapy water affect the number of drops that can fit on a penny?
2. How does adding different types of detergents (not just soap) affect the surface tension of water measured by the penny technique?

Step4: Make claim and provide evidence for water - strider question

Claim: Water striders would have difficulty walking on lakes contaminated with soap.
Evidence: Since soap decreases the surface tension of water (as seen from fewer drops of soapy water fitting on a penny compared to tap - water), the reduced surface tension would not support the weight of water striders as effectively.

Answer:

1. Independent: Type of water (soapy water or tap - water); Dependent: Number of drops that can fit on a penny
2. Control: Tap - water; Purpose: To provide a standard for comparison to observe the effect of soapy water
3. How does the concentration of soap in soapy water affect the number of drops that can fit on a penny? How does adding different types of detergents (not just soap) affect the surface tension of water measured by the penny technique?
4. Claim: Water striders would have difficulty walking on lakes contaminated with soap. Evidence: Soap decreases the surface tension of water (fewer drops of soapy water fit on a penny compared to tap - water), so reduced surface tension won't support water striders effectively.