Biology » Introduction to Biology » The Scientific Method

How Science Works

The Methods of Biology: Observing and Hypothesizing

Even though biologists and other scientists study many different types of things, they all use the same basic steps. The common steps they use to do research and answer questions are called scientific methods. Scientists often figure out questions to ask and answer just by observing the world around them.

Science investigation and research requires many skills and processes to come together in order to be successful and worthwhile.

  • To be accepted as a science, the methods mentioned above for broadening existing knowledge, or discovering new things, are generally used.
  • These methods must be repeatable and follow a logical approach.
  • The methods include formulating hypotheses and carrying out investigations and experiments to test the hypothesis.
  • Crucial skills are making objective observations, taking measurements, collecting information and presenting the results in the form of drawings, written explanations, tables and graphs.
  • A scientist must learn to identify patterns and relationships in data.
  • It is very important to then communicate these findings to the public in the form of scientific publications, at conferences, in articles or TV or radio programmes.

What is the scientific method?

The scientific method is the basic skill process in the world of science. Since the beginning of time humans have been curious as to why and how things happen in the world around us.

The scientific method provides scientists with a well structured scientific platform to help find the answers to their questions. Using the scientific method there are very few things we can’t investigate. Recording and writing up an investigation is an integral part of the scientific method.

A step-by-step guide to the scientific method

1. The question

Scientists are curious people, and most investigations arise from a scientist noticing something that they don’t understand. Therefore the first step to any scientific investigation is:

  • Ask a question to which you want to find an answer.
    1. What is happening?
    2. How is it happening?
    3. When is it occurring?
    4. Why is it happening?
  • Example: A farmer notices that his tomato plants that are shaded have smaller tomatoes than his plants that are in a sunny spot, which makes him wonder: ‘Does the amount of sunlight a tomato plant receives affect the size of tomatoes?’
A step-by-step guide to the scientific method

A step-by-step guide to the scientific method.

2. Introduction

Once you have a general question, background research needs to be undertaken. Your background research will ensure that you are not investigating something that has already been researched and answered. It will also tell you about interesting connections, theories, explanations and methods that people have used in the past to answer questions related to yours.

Science always builds on the work of others, and it ensures that our theories are constantly improved and refined. It is important to acknowledge the work of the people upon whose work your theory relies in the form of referencing. It is also vital to communicate your findings so that future scientists can use use your work as a basis for future research.

3. Identify variables

Your background research will help you identify the factors that influence your question. Factors that might change during the experiment are called variables.

  • Firstly think of all the relevant variables you can change.
  • Secondly think of all the variables you can measure or observe.

Different types of variables are given special names. Below is a list of some important variable types:

  • The dependent variable is the thing that you want to measure or investigate.
  • The independent variable is a factor (or factors) that changes which will have an effect on the dependent variable.
  • In every experiment you need to know which independent variable you are testing, and keep all the other possible variables constant. We call the the variables we keep constant fixed variables, or controlled variables

Example: In this investigation, variables might include: the amount of sunshine, the types of soil in which the tomatoes are growing, the water available to each of the plants, etc. To which variable type does each factor belong?

  • Dependent variable is the one you measure to get the results, e.g. the mass of tomatoes
  • Independent variable is the ONE thing you vary to see how it affects the dependent variable, e.g. how much light the tomatoes are exposed to (dark / dim light or shade / bright light)
  • Fixed/ Controlled variables are kept the same in all trials under investigation, because they may interfere with the results. All tomato plants will:

    1. Be the same species of tomato
    2. Get the same fertiliser (type and amount)
    3. Grow in the same type of soil
    4. Grow in the same type of container
    5. Get the same amount of water
    6. Can you think of more?

4. Hypothesis

Write down a statement or prediction as to what you think will be the outcome or result of your investigation. This is your hypothesis. The hypothesis should:

  • be specific
  • relate directly to the question you are asking
  • be expressed as a statement that includes the variables involved (the `cause’ and `effect’)
  • be testable
  • not expressed as a question but rather as a prediction
  • be written in the future tense

Example: During your background research you would have learnt that tomatoes need sunshine to make food through photosynthesis. You may predict that plants that get more sun will make more food and grow bigger. In this case your hypothesis would be: I think that the more sunlight a tomato plant receives, the larger the tomatoes will grow’.


A scientific investigation does not aim to prove a particular event occurs or a particular relationship exists. Rather, an investigation shows that it cannot disprove a particular suggestion or prediction. Therefore, it is important to note that an incorrect prediction does not mean that you have failed. It means that the experiment has brought some new facts to light that you might not have thought of before. 

To test the hypothesis in life Sciences, you can follow the step-by-step guide which is outlined below.

5. Aim

  • In the aim you need to state what you going to be investigating.
  • Key words you can use are:
    1. To determine…
    2. To show that…
    3. To investigate…
    4. To find out…
    5. To observe…
    6. To measure…

Example: In this case, your aim would be: to investigate the effect of different amounts of sunlight on tomatoes.


In science we never ‘prove’ a hypothesis through a single experiment because there is a chance that you made an error somewhere along the way, or there may be an alternate explanation for the results that you observe. What you can say is that your results SUPPORT the original hypothesis.

Optional Video: The Times and Troubles of the Scientific Method

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