How to Evaluate Scientific Questions

Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

Learn about what makes a good scientific and testable question. Then look at various ways to improve non-scientific questions to make them more scientific.

What is a Scientific Question?

Humans are naturally curious. We love to ask questions about the world and how it works. This is what led us to explore the world and spread to every corner of our planet. It's how we learned to farm, create steam engines, fly, and travel to the Moon. But not all questions are the same. There are the kind of questions regular people ask, and then there are the kind of questions scientists ask.

A scientific question is a question that is written in a way that is helpful for completing scientific investigations. A scientific question is one where an investigation can be designed and completed to find out the answer without having to do multiple, entirely different investigations to get there. In a word, a scientific question is testable.

A testable question is one that asks about objects, organisms or events found in the world around us. It can be answered through experiment, observation, or other data collection, by analyzing measurable data and evidence. And a testable question is one based on scientific ideas, not opinions, morals or other subjective things. The answer should be objective and clear.

Science is about collecting data.
Science is about collecting data

In this lesson, we're going to talk about how to evaluate questions and then adapt them into more scientific ones.

Evaluating Scientific Questions

When you come up with a question for a scientific investigation, it's important to evaluate that question. You need to ask yourself:

  • Is the question a worthwhile one to ask in the context of science or society?
  • Is the question specific enough - not too broad?
  • Is the question a single question, or are multiple questions hiding inside it?
  • Is the question testable?
  • Can the question be boiled down to two variables - how one variable affects one other variable?
  • Does my question and hypothesis fit together properly?

Once you've thought about whether your question fits each of these criteria, you might find that there's room for improvement. You should be able to answer 'YES' to all of the above questions. If there's even one 'NO,' you'll need to adapt your question into a more scientific one.

Turning Non-Scientific Questions Into Scientific Ones

Let's take a look at some examples of questions that fall short, and how they can be fixed.

Importance & Value

When it comes to importance, it's rather a subjective question. However, figuring out whether your question is valuable generally involves two things: science and society. Does your question answer something that is not yet studied well enough in previous scientific research? And could answering your question lead to genuine steps forward for society? If either or both of these things are true, then it's a strong question.

For example, a question like, 'How do rainbows form?' is something that scientists already understand, and might not be worthwhile. But 'How does the number of fuel cells affect the efficiency of an electric car?' will help us produce better electric cars in the future, and could be great for society.

Another way that a question can lack importance is if it is weirdly specific: Like asking 'How did the number of paving stones on Smith Street in Alexandria, Virginia affect the amount of traffic on that street?' There is likely very little reason to study such a topic on a single street.

Broad Questions

When people wonder about the world, they tend to ask very general questions. We ask questions like: Why is the sky blue? Or, how is a cow stomach different to a human stomach? Scientific questions need to be more specific than that. There needs to be a simple investigation that you can do to directly answer the question. A general question might contain multiple scientific questions that, together, would answer that general question. For example, within the question about why the sky is blue, you might have all of the following questions:

  • What is light?
  • What causes objects to be (or appear) different colors?
  • Why do eyes perceive different colors?
  • What is the difference between the light of different colors?
  • What substances make up the air?
  • What happens to the light from the Sun when it interacts with the particles in the air?

Even these questions are not perfect, and some of them are more general than we might like. After learning more about the situation, you might ask more specific questions like: what wavelengths of light do we receive from a blue sky? Or, what intensities of light do we receive from the sky at different positions relative to the Sun? Or, which wavelengths of light does each gas found in the atmosphere absorb? Answering all of these questions together, can lead you to an answer for the general question of why the sky is blue.

Why is the sky blue?
Why is the sky blue?

Though sometimes, the issue is not with a question containing multiple scientific questions. Sometimes a question is simply badly written and needs to be made more specific. For example, someone might ask: How much water do plants need to grow? Instead you could ask: How does the amount of water provided each day affect the rate at which a tomato plant's height increases?

Asking questions about tomato plants
Asking questions about tomato plants

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