For example, you may notice that the potted plant you place on the windowsill is taller than the plant you keep in your bedroom, even though they’re the same type of plant and you planted them at the same time. You may then ask why it is that the two plants have different growth rates.
For example, if you’re looking for information to answer your question about plants, you might start by looking up information on plant biology and photosynthesis from a science textbook or online. You may also find that gardening books and websites useful. You want to read as much about your question as possible, because the question may have already been answered, or you may find information that will help you form your hypothesis.
Your hypothesis should sound like a statement of fact. For example, your hypothesis might be that it was the greater amount of sunlight on the windowsill that caused your first potted plant to grow faster than the second. Make sure that your hypothesis is testable. In other words, it needs to be something you can prove in a scientific experiment.
Your prediction should be in the form of an if-then statement. For example, you might say, “If a plant receives more direct sunlight, then it will grow at a faster rate. ”
For example, you should list precisely how much soil you put in each pot, how much water you give each plant and how often, and how much sunlight each plant receives (measured in watts per square meter). Reproducibility is one of the key underpinnings of the scientific method, so it’s important that you lay out exactly how your experiment is conducted to ensure that others can copy it and try to get the same results.
For example, in the potted plant experiment, the independent variable would be the amount of sunlight each plant is exposed to. Your dependent variable would be the height of each plant.
For example, you can design an experiment in which you place 3 different potted plants (of the same species) in 3 different locations: 1 on the windowsill, 1 in the same room but in an area with less direct sunlight, and 1 in a darkened closet. You would then record how tall each plant grows at the end of each week for a 6-week period. Be sure you’re only testing a single phenomenon at a time. All other variables should be constant across your samples. For example, all 3 of your plants should be in the same size pots with the same type and amount of soil. They should also get the same amount of water at the same time each day. For some complex questions, there may be hundreds or thousands of potential causes and it can be difficult or impossible to isolate them in any single experiment.
It’s very important that you make it possible for other scientists to precisely copy everything you did when they repeat your experiment. This allows them to rule out that your results came from any discrepancies or mistakes. [8] X Research source
In the potted plant example, place each plant in the areas with differing amounts of sunlight that you selected. If the plants have already grown above the soil line, record their initial height. Water each plant with the exact same amount of water on a daily basis. At the end of each 7-day period, record each plant’s height. You should run your experiment several times to make sure that your own results are consistent and to weed out any anomalies. There’s no set number of times you need to repeat an experiment, but you should aim to repeat it at least twice. [9] X Trustworthy Source Science Buddies Expert-sourced database of science projects, explanations, and educational material Go to source
You can analyze your data by looking for certain patterns or proportional relationships within your results. For example, if you notice that the plants with more sunlight grew more quickly than the plant left in the dark, than you can deduce that the amount of sunlight had a directly proportional relationship to the growth rate. Whether the data confirms or fails to confirm the hypothesis, you must always be on the lookout for other things, so-called “confounding” or “exogenous” variables, that may have influenced the results. If this is the case, you may need to redesign and repeat your experiment. In more complicated tests, you may not be able to figure out whether your hypothesis is confirmed without first spending considerable time looking at the data you gathered in your hypothesis testing. You may also find that your test is inconclusive if it fails to either confirm or fail to confirm your hypothesis.
For example, you might consider publishing your findings in a scientific journal like Nature or at an academic conference hosted by a local university. The format in which you communicate your findings will largely be determined by the venue. For example, if you’re presenting your findings at a science fair, you may find that a simple poster board will suffice.
For example, if your potted plant experiment showed no significant relationship between the amount of sunlight received and the growth rates of your three plants, you should consider what other variables might explain the difference in plant height you witnessed before. These could be the amount of water you use for each plant, the type of soil used, etc. Even if your hypothesis is confirmed after 1 experiment, further research will be necessary to ensure that the results are reproducible and not just a one-time coincidence.
