Sara and Juan conducted an experiment to test which soil would be BEST for growing plants. They used all three types of soil seen in the jar: sand, silt,
and clay. They also made a mixture of soil using equal parts of sand, silt, and clay. They planted bean seeds in four pots and placed the pots in the sunlight. They watered the pots every day and tracked the seed germination and plant growth.

Which of these BEST reflects a possible hypothesis for the experiment?
A) The bean seeds will grow faster in warmer weather.
B) The bean seed in the pot of silt will grow fastest.
C) The bean seeds will all take three weeks to sprout.
D) The color of the pots will affect the growth of the seeds.

Experimental design should be developed to prove one or more hypothesis. Therefore, between all choices from the multiple-choice, the only hypothesis that they can test is that the bean seed in the pot of silt will grow fastest.

In an experiment, you should control all possible variables, except one, the treatment. In this case, all seed should receive the same weather (a), and the color of pots should be the same (d). The time that will take beans to sprout (c) is the response variable that will be measured. Treatments, in this case, soil type (b), should be different to prove the hypothesis.

The independent variable in this experiment is the soil type, and the dependent variable is time to sprout.