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How do I determine which of the following observations are testable, and how would I...

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How do I determine which of the following observations are testable, and how would I write a hypothesis and null hypothesis and determine my experimental approach?

1.When a plant is placed on a windowsill, it grows faster than when it is placed on a coffee table in the middle of the living room.

2. The teller at the bank with brown hair and brown eyes and is taller than the other tellers.

3.I caught four fish at seven o'clock in the morning but didn't catch any at noon.

4. The salaries at Smith and Co. are based on the number of sales and Billy makes 30,000 more than Joe.

5.When Sally eats healthy foods and exercises regularly, her blood pressure is lower than when she does not exercise and eat fatty foods.

6.The Italian restaurant across the street closes at 9 pm but the one two blocks away closes at 10 pm.

7. Bob bought a new blue shirt with a golf club on the back for twenty dollars.

8. For the past  days the clouds have come out at 3pm and it has started raining at 3:15.

9. George did not sleep at all last night because he was up finishing his paper.

10. Ice cream melts faster on a warm summer day than on a cold winter day.


As you can see I am having a little trouble wrapping my brain around the scientific method. I am hoping that by knowing which of these observations is testable, I might better grasp the method and approach.

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From the scenarios that are outlined above, it is interesting to first note that very few are actually designed to solve pressing scientific questions. As such, a useful starting point may be noticing that the scientific method is a useful and systematic way to go about resolving all sorts of problems. Fundamentally, and as a basic way of thinking about it, consider the scientific method as a way to ask and answer questions. In science, one of the key questions to ask is “why.” As such, start by asking a few “why” questions that are of interest to you.

The fun thing about the scientific method is that you can ask about any reasonable question that can be supported by reasonable evidence, observations, and experiments. It might help first to rank order the list above 1-10 in terms of the best, or most testable “why” questions that can be asked and answered for each scenario. For example, in the first scenario, try asking a question such as “Why does a plant grow at a different rate in a different place?” Try to ask questions that indicate that they can be answered with a specific experiment in mind. Avoid asking a vague question that cannot be measured, such as “Why is the plant so big over here rather than over there?“ Also avoid asking a question that is somewhat silly and cannot be measured through an experiment, like “Why does it look like the cat ate the plant by the windowsill?“

Next, a helpful way to approach a hypothesis is to think of it in terms of answering the research “why” question that has been asked. So, start with a few statements that begin with “because.” As such, a few “because” statements may be “because the plant is cold” or “because there is more sunlight by the windowsill.” Hypotheses can be a little tricky because you may set out to prove it right, when actually according to further research, observations, and experiments, it is, in fact, wrong.

Finally, the hypothesis would be stated in terms of a variable and control around which an experiment could be designed. Again, almost any variable and any control can be identified for an experiment, just be sure not to be vague or silly. In the first example, try “Plants grow at a faster rate at the windowsill when exposed to sunlight.” Or, conversely, “Plants grow at a slower rate on the coffee table when exposed to cold.” In the first hypothesis, the experiment would center around varying, measuring, and comparing the amount of sunlight at the windowsill vs. the coffee table. In the second, the experiment would center around varying, measuring, and comparing the temperatures in both locations.

Again, this can be a tricky spot because the experiment would need to be controlled down to very specific details: the same type of plant in both locations, given the same amount of water at roughly the same time, etc. It is not wise to develop and test hypotheses for which variables cannot be strictly controlled. Included is a helpful eNotes reference as well as an example of a controlled experiment. Good luck!


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