Victor made the graph shown to record the observations of an experiment to study the effect of soll additives on the growth of plants. Three identical plants having a height of 25 cm were used for the experiment. The first plant had no soil additives, the second plant had wheat straw in the soil, and the third plant had polymer in the soil. All other growing conditions of the plants were kept constant.

1) The correct step in the scientific method that Victor did is Construct a hypothesis.

2) Given mass and density, volume is calculated as mass divided by density.

Explanation:

1) Before doing the assay and make a graph with the results obtained, Victor should think what he wants to prove, so he should make a hypoythesis to test with the assay.

2) The formula of density is

density = mass/volume ⇒ density x volume = mass ⇒                      volume = mass/density.