Good Afternoon!

1. Good Afternoon! • Come in Quietly. Turn in your science contract but HOLD ON TO YOUR HOMEWORK! We will check this in class. • Copy down your homework from the large white board • Get started on your bell ringer activity • Music is off because yesterday some people in the class could not be quiet while completing their morning work. You will earn your right to music back if work is completed quietly.

2. Reminder • When you leave push in your chairs, make sure your tables are in the correct position, your trash is put away, and make sure your journals are NEATLY stacked up.

3. What is a variable?

4. Scientists use an experiment to search for cause and effect relationships in nature. In other words, they design an experiment so that changes to one item cause something else to vary in a predictable way. • These changes are called variables.

5. Variables… • There are two main types of variables in science • Independent - The one YOU have control over and YOU can change. • Dependent – What you measure. This variable DEPENDS on the independent variable. • Example - If I use a new fertilizer, then my plant will grow taller. • Which is the independent variable? Which is the dependent variable?

6. Variables continued… • In an IF…THEN.. Statement, the “IF” is the independent variable and the “THEN” is the dependent variable. • If I do not study for my test (Independent Variable, THEN I will fail (dependent variable- depends on the independent variable)

7. Controls • Controls are CONTROLLED variables. • These do not get to play along in the experiment. It is the part of the experiment that is unchanged and does not have an independent variable. These must be carefully monitored to have accurate results. • In the example we used earlier – (If I use a fertilizer, then my plants will go taller. A control could be the plant that did not have fertilizer added, it has not been affected by the independent variable – the fertilizer).

8. Constants • Constants in an experiment are things that remain the same. If you are testing an experiment, you would change one thing (Independent variable) and keep everything else the same (constant).

9. Example: • A scientist was trying to see if the amount of water a plant gets affects plant growth. She collected 10 identical plants and gave them different amounts of water. She measured their growth daily. The plants received the same amount of sunlight. • Independent variable: • Dependent variable: • Control: • Constants:

10. Example 2: • A scientist was trying to determine if the shape of hot air balloons would affect how high they went. The shape of 10 hot air balloons was varied. Some were oval; some were round. The altitude (how high they went) was measured. the scientist tested them on the same day so the weather conditions would be the same. The balloons were the same size. • Independent variable: • Dependent variable: • Control: • Constant:

11. Video on Variables • http://www.youtube.com/watch?v=x2606GQmDqY

12. Practice • http://classtools.net/widgets/dustbin_8/GVIai.htm

13. Independent practice • Complete the variables worksheet

14. Independent work/Homework • Create 5scenarios with an independent and dependent variable. Label what is the independent variable and what is the dependent variable. Use “If…Then” statements for each scenario. • If I water my fig plant three times a week then my plant will grow taller. • Independent Variable – frequency of watering • Dependent Variable – Plant Growth

15. Example