How to Design an Experiment that Focuses on a Land Use Issue

As your group conducts research on your particular land use topic, you will find that certain environment issues are discussed. For example, a citizen’s group may be concerned that increased erosion will occur if trees are cut down to build homes. This erosion could cause more sediment to be washed into a local stream. The increase in sedimentation could cause fish and fish eggs to die. Your group could design an experiment that asks, “How would increased sedimentation in the Local River affect the fish populations?”

Designing an Experiment

Question:

Hypothesis:

Independent Variable (IV):

Dependent Variable (DV):

Materials:

Procedure:

1.

2.

3.

4.

etc.

Control:

Constants:

Designing an Experiment

Vocabulary

1. Question: All scientific investigations begin with a question that can be answered by collecting evidence. “What amount of fertilizer produces the most tomatoes” is a good question for experimentation.

2. Hypothesis:

• a prediction about the outcome of the experiment;
• a prediction based on past experience, prior knowledge or observations
• must be able to be tested
• written in the form “ If I give the tomato plant 4 grams of fertilizer than the plant will produce the most tomatoes.”

3. Variable: any factor that can be changed in an experiment.

4. Independent Variable: the factor or variable that is purposely changed by the experimenter. The amount of fertilizer is the independent variable.

5. Dependent Variable: the factor that responds to the changes in the independent variable. It is what you measure or observe to obtain your results. The number of tomatoes is the dependent variable.

6. Materials: a list of materials that you will need to conduct the experiment. Units of measure should be included when necessary.

7. Procedure: the step-by-step directions for conducting the experiment. The procedure should be clear enough so that another person would be able to replicate the experiment.

8. Control: the level of the independent variable chosen as the standard of comparison. A control can be chosen in one of three ways.

1. the level at which the IV is omitted,
2. the level suggested by an outside standard (for example, according to package instructions, or
3. in the case of comparisons, the level selected by the experimenter (your choice)

In the fertilizer experiment, the plant with no fertilizer could be the control. Or, the control could be the amount suggested in the directions.

9. Constants: the factors, which remain the same for each, repeated experiment. In the fertilizer experiment, the constants would include but not be limited to: the amount of water given to each plant, the size and type of pot, and the type of plant.