Parts of a Controlled Experiment

I gave plot A one gallon of water per week. I gave plot B two gallons of water per week. After 4 weeks, the grass in plot B was taller than in plot A Can I say for sure that water affects the height of grass? A B

 1. Testable Question  Def: This is a question that can be answered by an experiment  Usually only one factor at a time is investigated  Good examples:  ***Does the amount of fertilizer affect the number of flowers on a plant?  Is a person’s heart rate affected by 5 hour energy?  Bad example:  Why is the sky blue?  What happens after you die?

 2. Hypothesis  A hypothesis is NOT an educated guess!  Def: A hypothesis is an explanation or prediction that can be tested

 Good examples:  Does the amount of fertilizer affect the number of flowers on a plant? ***I think adding fertilizer will cause a plant to produce more flowers  Is a person’s heart rate affected by 5 hour energy? I think 5 hour energy does not affect a person’s heart rate  Bad example:  Why is the sky blue? I think blue is pretty  What happens after you die? I think I’ll be reincarnated as a unicorn

3. Independent Variable Def: One factor that is changed on purpose to see if it has an effect on whatever you’re testing Does the amount of fertilizer affect the number of flowers on a plant? ***The independent variable would be the amount of fertilizer 4. Dependent Variable Def: What you measure or observe as a result Does the amount of fertilizer affect the number of flowers on a plant? ***The dependent variable would be the number of flowers that grow on the plant 5. Controls Def: The things that are the same for all experimental groups Ex: ***water, sunlight, temp.

6. Materials Def: A list of what is needed 7. Procedure Def: Step by step instructions Why is it important to write a good materials list and procedure? Your experiment needs to be able to be repeated so that someone else can see if they get the same results that you did 8. Data Def: Information collected from the experiment (with units) organized in a table and/or graph

Title Independent Variable Depend. Variable Start at 0

 9. Analysis  Def: An explanation of the data  What does the data tell you?  Example: Because all of the plants produced the same number of flowers, that must mean that fertilizer does not affect the number of flowers on a plant.

 10. Conclusion  Def: A summary of the experiment. Includes what was learned and real world connections.

I gave plot A one gallon of water per week. I gave plot B two gallons of water per week. After 4 weeks, the grass in plot B was taller than in plot A Can I say for sure that water affects the height of grass? A B

 No! More than one factor is being changed. In this example it is water and sunlight. A B