Warm Up 8/13/13 1. What is an independent variable? 2. What is a dependent variable? 3. What are control variables?

Objective: I will be able to identify an independent and dependent variable as evidenced by writing a sample experiment

Identifying Variables  Underline the independent variable  Double Underline the dependent variable  Circle the control variables

Example 1 Sam wanted to know if the amount of light affects the growth of plants. He gets 10 plants and places them so they each get a different amount of light. He uses the same type of plant, soil, and pot. Each plant gets the same amount of water as well. At the end of two months he measured the height of each plant.

Example 2 Jenny wanted to know if there was an ideal temperature to store fruit to keep it from rotting really quickly. She bought 12 oranges from the store and put 4 oranges in a clear glass bowl in the refrigerator, 4 oranges in a clear glass bowl on the counter, and 4 oranges in a clear glass bowl by a sunny window. She left them there for a week and then observed the amount of change.

On the left side…  Page 18  Variable Practice

Variable Practice  With a partner, read the four examples on the worksheet.  Identify the independent, dependent, and control variables.  On your own, write two sample experiments in the blanks at the bottom of the page.  Identify the independent, dependent, and control variables.  Underline the independent variable  Underline the dependent variable  Circle the control variables

Ricky thinks the price of gas determines how much a person will buy. Each day he changes the price of gas and measures how much gas the same people buy.

Isabel thinks that eating sugar affects how many cavities you get. She has 10 people eat different amounts of sugar each week and measure how many cavities each person gets. They all brush their teeth twice a day.

Juan thinks that light make fruit go bad. He takes 20 red apples and puts them in different amounts of light. He measures how much time it takes each apple to go bad.

Karis thinks that people who are absent less get better grades. She looks at how many days 8 th grade students are absent in her school and measures their grades.