What is Scientific Investigation? - Definition, Steps & Examples

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  • 0:01 Scientific Investigation
  • 2:09 Steps for Scientific…
  • 6:47 Lesson Summary
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Lesson Transcript
Instructor
Scott van Tonningen

Scott has a Ph.D. in electrical engineering and has taught a variety of college-level engineering, math and science courses.

Expert Contributor
Amanda Robb

Amanda holds a Masters in Science from Tufts Medical School in Cellular and Molecular Physiology. She has taught high school Biology and Physics for 8 years.

Scientific investigation is the way in which scientists and researchers use a systematic approach to answer questions about the world around us. Read on to find out more. A quiz is provided to test your understanding.

Scientific Investigation

Some time ago, I was asked to be a judge at a local school science fair. I went to the school to do my judging duty and there were the usual projects: Alaina had a volcano that erupted a vinegar and baking soda mixture; Phillip displayed a three-dimensional mobile of the solar system; and Mariah discussed a potato in a jar of water with a plant growing out of it.

But I was looking for something more. Was there a kid there that really wanted to conduct a scientific investigation? Then I found it. Back in the corner of the gym was a small table and an even smaller boy with a rather crudely made poster. It read, 'How does the angle of a ramp affect how fast a toy car will roll down?' I quickly made my way over to the boy's station and saw that he had an experimental setup with a long wooden ramp and a way to measure the angle of the ramp. He also had a toy car and a stopwatch. Perfect!

Intrigued, I asked him a number of questions. What is your hypothesis? How would you describe your experimental setup? What were your results? Did they support your hypothesis? What about errors in your measurements? Calmly, the boy answered each question and then showed me this table with results scrawled in:

Experimental data from the car and ramp
Car and ramp experiment data

After a long discussion with the lad, I came to the conclusion that he had conducted a thorough scientific investigation and had learned much from this experience. I voted for an 'A' grade! Let's find out more about what constitutes good scientific investigation.

Scientific investigation is a quest to find the answer to a question using the scientific method. In turn, the scientific method is a systematic process that involves using measurable observations to formulate, test or modify a hypothesis. Finally, a hypothesis is a proposed explanation for some observed phenomenon, based on experience or research. Scientific investigation is what people like you and me use to develop better models and explanations for the world around them.

Steps for Scientific Investigation

As you can imagine, there are several phases to a good scientific investigation. These may vary a bit in the literature, but they generally include five steps.

Step one - Observe something of interest

The young man at the science fair obviously enjoyed playing with toy cars and had noticed that when he increased the pitch of the ramp, the cars went faster. He wondered what the relationship was between the steepness of the ramp and the speed of the car, beyond just the obvious fact that it went faster as the slope increased. People who engage in a scientific investigation usually do so because they don't know or are unsure of some aspects of the observation or because they want to confirm a hunch about the observation.

Step two - Formulate a question that can be answered in a measurable way

It's important to ask the question so that it can be answered in a measurable way. Beginning the question with 'what,' 'how' or 'why' is a good start. The question should also be focused. Many researchers make the mistake of trying to 'boil the ocean' with a question that is too general. For example, 'Why do people get sick?' would not lend itself to a good scientific investigation in anyone's lifetime, even though it's a pertinent question. Remember, boiling the ocean is quite a bit more difficult than boiling a pot of water.

Step three - Formulate a hypothesis that answers the question based on experience or research

You may be wondering, 'Why come up with a hypothesis about something we're trying to discover?' It's much easier to analyze data and compare it to an existing theory than to try to develop a theory from scratch. There are already good models for much of what we observe, so we can usually find the seeds of an answer to our question through research. Many times, scientific investigation is used just to make incremental improvements to a theory, process or product. In short, the hypothesis brings to bear all that is already known about the question; it gives us context for what we're studying.

When I asked the young boy about his hypothesis, he said, 'When I play with my cars, I notice that when I start increasing the slope of the ramp, the speed of the car seems to change a lot. Later on, at the higher slopes, the car goes fast but each change seems to have less effect. My dad's a teacher and when I talked to him about this, he said that the force of gravity goes straight down. So the part of gravity that is affecting my car changes with the angle, but it changes less at the higher angles. He said it has something to do with trigonometry. I don't know what that is. Anyway, that's what I am expecting to happen.'

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Additional Activities

Applying the Scientific Method

After learning about the methods for scientific investigation, it's time for students to apply this for themselves. Guide students towards a testable question, like the affect of sunlight on plants, or how weather affects attendance at school. Questions should be testable, and be able to be answered in the lab or through repeated observations.

Directions:

Now it's time to start your own scientific investigation! In this activity you will be carrying out a scientific investigation about something you are interested in. Before you get started, you want to make sure that your question is testable and measurable. Good scientific questions have a definitive answer and aren't open ended. An example of a good question is, "How does fertilizer affect plant growth?" This is simple, measurable and can be done in the lab. A poor scientific question might be, "Where did life come from?" We can't answer this in the lab, and there aren't good tests to answer it either!

  1. Observe the natural world and brainstorm a question that you want to find the answer to.
  2. Do some background research on the question so that you can create a hypothesis, or an educated guess about what will happen. Write your hypothesis down. For example, in our plant example above a hypothesis might look like, "If we add fertilizer then the plants will grow taller because fertilizer contains limiting growth factors that plants need."
  3. Next, write down the procedure for how you plan to test your hypothesis, then carry it out. For example, in the plant experiment, the student might include steps to set up the plants in identical pots, how much water and sunlight each plant will be given, and how much fertilizer one plant gets and when.
  4. Collect your data in a table based on the two variables you are testing. In our plant experiment, the table might look like this:

ConditionHeight on Day 1Day 2 Day 3
Fertilizer
No fertilizer
  1. Next, it's time to analyze your data. Was your hypothesis supported or not supported?

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