Scientific Method

Control Variable:

The elements within an experiment that remain constant or unchanged

Manipulated Variable:

The one element within an experiment that is changed or varied throughout an experiment

Responding Variable:

An observed change within the experiment that happens as a result of a change in the manipulated variable

How the scientific method works via experimentation

  1. Formulate a question

    • Do plants need sunlight to grow
  2. Research the question (Maybe the question has already been answered!)

    • Plants convert light into energy using chlorophyll
  3. Form a hypothesis

Hypothesis is written in a form called if...then statement (If we change this then this will change as a result)

If we adjust the volume knob on the radio, 

then the radio will play louder.

If we flick on the light switch, 

then the lights will light up.

Now we sprinkle in Manipulated Variable and Responding Variable into the hypothesis:

If the Manipulated Variable is describe change,

then the Responding Variable will describe change.

If the light given to a plant is increased then the plant growth will increase

4. Following a method or procedure carry out the experiment

  • Grow plants in dark vs. grow plant in light

5. Collect data

  • Plant that was grown in light grew 10 cm! OMG!

6. Analyze and discuss Data

  • Answer questions about the data
  • Are there any patterns or trends you notice with the data?

7. Discuss Reliability and Validity of the experiment


Means the experiment is actually testing the hypothesis 

  • If i'm testing plant growth is an experiment testing a plants taste really valid? 


Means the experiment can be repeated with consistent results

  • No matter how many times I do the experiment i should get the same results
  • Are there parts of the experiment that can change results when repeated ?
  • Any follow up questions after the experiment
  • Is there a better way to conduct the experiment

7. Conclusions - Based on data we either accept or reject hypothesis

  • (Fancy-sciencey way to say the hypothesis is true or not) 
  • Re-state hypothesis, followed by 'is accepted' or 'is rejected', and why.

The hypothesis that: If the light given to a plant is increased then the plant growth will increase, is accepted. The data shows that as we increased the amount of light, the height of the plant increased, thus supporting our hypothesis.