A student decides to set up an experiment to see if detergent affects the growth of seeds. He sets up 10 seed pots. 5 of the see
d pots will receive a small amount of detergent in the soil and will be placed in the sun. The other 5 seed pots will not receive detergent and will be placed in the shade. All 10 seed pots will receive the same amount of water, the same number of seeds, and the same type of seeds. He grows the seeds for two months and charts the growth every 2 days. What is wrong with his experiment? A) There is no appropriate control
B) There is no way of measuring the outcome
C) More than one variable is being tested
The correct answer is option C) "More than one variable is being tested".
Explanation:
One of the basis of scientific experimentation is to test one variable at the time in order to make sure that the response that is being obtained is the result of that variable and not another one that is not taking into account. In this case, the student is making the mistake of assessing two variables at the same time: the use of detergent and placing the plant in the sun or in the shade. At the end of the experiment the student will not know if the response is the effect of the detergent, the exposure to the sun or a combination of both.
In the experiment several variables are being studied, such as the influence of detergent on seeds and the intervention of the sun or shade on seeds with or without detergent. It should be both groups of seeds in the sun or both groups in the shade.
