key science skills

Question 1

Define and identify independent and dependent variables

Answer 1

The independent variable (IV) is the factor or condition that the researcher manipulates or changes in an experiment to see its effect on the dependent variable. It’s what you think will have an impact on the outcome of the experiment.
The dependent variable (DV) is the outcome or result that you are measuring in the experiment. It is what you expect to change in response to the manipulation of the independent variable.
Independent Variable (IV): Amount of fertilizer (e.g., low, medium, high)
Dependent Variable (DV): Plant growth (measured in height, number of leaves, etc.)

Question 2

Formulate a directional hypothesis based on IV and DV

Answer 2

A directional hypothesis predicts the specific direction of the relationship between the independent variable and the dependent variable. It states the expected effect of the IV on the DV. For the fertilizer example:

Null Hypothesis (H0): There is no significant difference in plant growth between different amounts of fertilizer.
Directional Hypothesis (H1): Increasing the amount of fertilizer will lead to a significant increase in plant growth.

Question 3

Identify controlled variables

Answer 3

Controlled variables are factors that you intentionally keep constant or control throughout the experiment to ensure that they don’t interfere with the relationship between the independent and dependent variables. In the plant growth experiment, controlled variables might include:

Type of soil
Type of plant species
Amount of water
Light conditions
Temperature