Let us systematically break our problem into hypothesis, testable version of hypothesis, constant, and variables.
Hypothesis: In the experiment, you will determine whether having worms in the soil affects the growth of lima bean plants.
Variables: Independent variable - presence of worms, dependent variable - amount of growth in lima bean plants (measured as the change in length of the plant shoot)
Constant: Amount of soil, amount of water given to the plant.
Our question would be a testable version of the hypothesis.
1. Presence of worms in soil will promote growth of lima bean plants.
2. Presence of worms in soil will stop the growth of lima bean plants.
Null hypothesis: Presence of worms in soil will not affect the growth of lima bean plants.
While trying to answer the question our goal will be to first reject the null hypothesis by gathering evidence through experimental observation. Then, we will test the parts 1 and 2 of the testable hypothesis.