- A hypothesis is a statement or a proposition about how something operates. For instance a hypothetical statement could be, "sugar water helps roses grow faster." There is no proof when this statement is made, but it is a proposition that if you give sugar water to roses then it will help them grow at a rate that out paces roses given plain water. The variables come in when you test the hypothesis.
- A variable is any factor that can influence how a process takes place. For instance, if you have two sets of plants that are growing, variables include the time of year, soil nutrients, sunlight and even the amount of wind. Almost anything can be a variable, and the goal is to try to control the variables as much as you can when you are testing a hypothesis.
- If you are testing the hypothesis that sugar water helps roses grow faster, you need to plant two samples of the same rose in soil that is the same quality with the same nutrients. You need to make sure they both get the same exposure to sun and that everything is as similar as possible. The only variable you want to alter is the sugar water, which needs to be the only factor, if possible, that could explain differences in rose growth.
- Once you have gone through an experiment and obtained your results, you need to either reject the null hypothesis (in this case it would be "sugar water does not make roses grow faster") or fail to reject it. If you reject the null hypothesis then your results have shown that your original hypothesis was correct. If the results are not decisive though, or if you could not control enough variables, then you do not have enough information to be sure that your hypothesis is correct. This is why experiments are conducted over and over again to try to duplicate the same results.
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