1. VARIABLES

2.  Variables  Factors in an experiment that can change. VARIABLES

3.  Controlled Variable  Also called a “Control or Constant.”  A factor or condition that stays the same in an experiment. VARIABLES

4.  Independent Variable  Also called a “Manipulated Variable”  Think… I CHANGE this variable (I as in you)  A factor or condition that is intentionally changed by the investigator in an experiment.  The factor you wish to test! VARIABLES

5.  Dependent Variable  Also called a “Responding Variable”  Think… DEPENDS on what I change (I as in you)  A factor or condition that might be affected as a result of change in the independent variable.  Factor you measure to gather results! VARIABLES

6.  Controlling Variables  Keeping all conditions the same except for the independent variable. VARIABLES

7.  Example:  Imagine an experiment to test how air temperature affects the rate at which ice melts.  What is the independent variable?  What is the dependent variable?  What are the controlled variables? VARIABLES

8.  Independent Variable:  Air Temperature  Dependent Variable:  Rate at which the ice melts  Controlled Variables:  Amount of ice  Shape of ice  Type of container VARIABLES

9. Jim, Jody, and Juan, all sixth graders, love to play tennis and are interested in forming an interscholastic tennis team. To do so, they decide to hold tennis practice sessions during period 4 every day. Mr. M, Mr. P, and Mr. S agree to hold tryouts at the end of October. Seeing as how this was their idea, Jim, Jody, and Juan want to make sure that they will make the team. To ensure their placement on the team, they test to see which brand of tennis ball helps produce the fastest serve. Jim, Jody, and Juan believe that if they determine the ball that produces the fastest serve, they will definitely make the tennis team because they will have an advantage over the other players. Before completing the experiment, they all think that brand X tennis balls will bounce the highest because they are the hardest to squeeze. Using brand X, Y, and Z tennis balls, they decide to drop each ball from 15 meters above the ground onto a clay tennis court. They measure the height that each ball bounces and record this value in their data table. Jim, Jody, and Juan complete five trials for each tennis ball and record an average height in their data table. SAMPLE READING #1: SCIENTIFIC SERVES BY CHRIS SHAYER

10.  What is the independent variable in the experiment?  What is the dependent variable in the experiment?  According to the passage, what was their hypothesis?  Name three constants involved in the experiment. SAMPLE READING #1: SCIENTIFIC SERVES BY CHRIS SHAYER

11. Alberta, Megan, and Tom are trying to grow the largest pumpkin for the state fair. They decide to use the greenhouse behind Mr. K’s room. They want to test which type of soil is best suited for growing pumpkins. Alberta, Megan, and Tom decide that if they can determine which type of soil is best suited to grow pumpkins, they will win the blue ribbon. Before completing the tests, they all think that potting soil will work the best because it contains plenty of organic material, which helps the soil hold water. They plant pumpkin seeds in regular dirt dug from behind the school, sandy soil found at Megan’s house, and store-bought potting soil. They fill three clay pots with the regular dirt and label them Pot A, Pot B, and Pot C. They also fill three clay pots with the sandy soil and label them Pot A, Pot B, and Pot C. Finally, they fill three clay pots the potting soil and label them Pot A, Pot B, and Pot C. In each pot, they plant the same species of pumpkin seed, water them with the same amount of water, and place them in the greenhouse so that they all get the same amount of sunlight. After the pumpkins grow, they measure how much each pumpkin weighs from each type of soil and record their findings. SAMPLE READING #2: PERFECT PUMPKINS BY DINA ROSSI

12.  What is the independent variable in the experiment?  What is the dependent variable in the experiment?  What was the hypothesis that Alberta, Megan, and Tom came up with in their experiment?  What are three constants in this experiment? SAMPLE READING #2: PERFECT PUMPKINS BY DINA ROSSI

13. Timmy, Tommy, and Tina want to plant a garden at their middle school. They have written a letter to Mr. B asking permission to use the land around school for their garden. Mr. B has agreed, but they can only use one area of the property for the garden. Before picking a spot, Tina, Tommy, and Timmy walk around the school to find the perfect location for the garden. Tina likes the spot behind the tennis courts, Tommy likes the spot behind the cafeteria, and Timmy wants the garden in the front of the school. All three of these areas are flat and receive the same amount of sunlight. Tina remembers working in the summer on her grandparents’ farm and her grandfather always saying, “To have a good crop you need good soil that holds lots of water.” To be fair to all, they agree to take samples of the soil at each spot and to perform an absorbency test to see which soil holds the most water. After taking the soil samples, they find that the front of the school has very sandy soil, the area around the tennis courts is made up of a clay-based soil, and the area behind the school consists of soil that contains decomposed organic materials from leaves, twigs, and grass clippings. After looking at the different types of soils, they all think that the clay-based soil will hold the most water and that the area behind the tennis courts will be the best place for the garden. To test for absorbency of the water, they place 50 g of each soil into a funnel with filter paper. Underneath the funnel is a beaker that will catch the water that seeps through the soil. Next, they pour 100 mL of water into the soil and record the amount of water filtered and absorbed. They test each soil five times to be sure that their results are accurate. SAMPLE READING #3: SOIL ABSORPTION BY STEVE MATYCZYK

14.  What is the independent variable in the experiment?  What is the dependent variable in the experiment?  What was the hypothesis that Timmy, Tommy, and Tina came up with in their experiment?  What are three constants in this experiment? SAMPLE READING #3: SOIL ABSORPTION BY STEVE MATYCZYK

15. “I feel that the sand will erode the least,” stated Jim. Jim and Sally were having a discussion about which type of sediment that made up the bed of Wakooie Stream would erode the least over time. “I think the small rocks at the bottom of the stream will erode the least because they are heavier than the sand,” said Sally. “The sand is going to erode the least because it is packed at the bottom of the stream, giving the sand particles extra strength to stay in place. I’m correct and you are wrong!” said Jim. Jim and Sally decided to investigate which type of particle at the bottom of Wakooie Stream would erode the least. Jim and Sally developed a test to see who was right. Jim and Sally took three different sediments from the streambed: sand particles, small rock particles, and large rock particles. They collected 100 mL of each sediment. Next, Jim and Sally took a 4-foot plastic container onto three blocks of wood that measured 5 inches in height. This created a ramp. Seven inches from the top of the ramp, Sally drew a square box. The square box that Sally drew was where they would place the sediment during each trial. Meanwhile, Jim measured 1,000 mL of tap water. Jim and Sally did the experiment once the materials were collected. First they placed the 100 mL of sand sediment in the square that was drawn by Sally. Then they poured the 1,000 mL of tap water from the top of the container, allowing the tap water to run into the sediment as it traveled downhill. The water was acting like the flow of a stream in this investigation. When the water came to a stop at the bottom of the container, Sally and Jim placed the soil that did not wash away (the soil remaining in the square Sally drew) into a 100 mL beaker and measured how much soil had been eroded away. Each type of sediment was test three times in this manner. After each trial was conducted, Jim and Sally found the average for how much soil eroded away and discovered which sediment eroded the least and which sediment eroded the most. SAMPLE READING #4: STREAMBED EROSION BY SHAWN PELLETIER

16.  What is the independent variable in the experiment?  What is the dependent variable in the experiment?  What was Jim’s hypothesis in the experiment?  What are three constants in this experiment? SAMPLE READING #4: STREAMBED EROSION BY SHAWN PELLETIER