Question

Another of your children does their science fair project on soap bubbles. They show you their data in the following table:

Expt # mL detergent mL water mL glycerine Time bubble lasted (s)

1 5 15 0 6

2 8 12 0 9

3 11 14 5 15

4 11 12 5 17

5 11 12 7 20

A. Which experiment(s) can be used to determine the effect of increased detergent (only)?

B. Which experiment(s) can be used to determine the effect of increased glycerine (only)?

C. In all of the experiments, what is the dependent variable?

D. What are some of the varibales which should have been controlled in all of these experiments?

Answer 1

A) Between experiments 2 and 4 it is observed that the amount of detergent increases, but that of glycerin remains constant, this allows us to observe the difference.

B) Between experiments 3 and 4 the increase in the amount of glycerin and constant detergent is observed.

C) The dependent variable is the duration of the bubble.

D) The amount of detergent and glycerin are the controllable variables.

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