300
The farmer predicts that taller plants will have more blossoms and performs the following experiment to test this hypothesis. Two groups of 10 plants each are grown in identical pots filled with equal amounts of identical soil. The amount of sunlight, the room temperature, and the amount of water are held constant for both groups. Group A is given plant food at regular intervals according to the instructions on the package. Group B is not given plant food.
• Explain why the amount of sunlight, the room temperature, and the amount of water were held constant for both groups.
What is they are all control variables needed to keep the experiment fair?