Identifying Variables In Experiments

Identifying Variables In Experiments

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Vocabulary Review

• Experimental Group receives the treatment or test material

• Control Group does not receives treatment or test material

• Independent variable is controlled by researcher, so ask the question, "What is different?"

• Dependent variable is responding to the independent variable, so ask the question, "What is measured?"

• Qualitative data describes something such as a blue truck.

• Quantitative data is numerical meaning numbers for example five cats.

Multiple Choice

Min wanted to find ways to save water. She learned that people can reuse greywater, which is water that has been used in sinks, tubs, and washing machines. She wondered if her plants would be less healthy if she watered them with greywater instead of tap water.

Min placed eight potted petunia plants on her windowsill. For three months, she water four of the plants with greywater and the other four with tap water. At the end of three months, she counted the number of dead leaves on each plant.

In this experiment, the plants watered with tap water were part of __.

• an experimental group

• a control group

Multiple Select

Min wanted to find ways to save water. She learned that people can reuse greywater, which is water that has been used in sinks, tubs, and washing machines. She wondered if her plants would be less healthy if she watered them with greywater instead of tap water.

Min placed eight potted petunia plants on her windowsill. For three months, she water four of the plants with greywater and the other four with tap water. At the end of three months, she counted the number of dead leaves on each plant.

What is the test material in the experiment?

• greywater

• tap water

Multiple Choice

Ava and her friends went swimming in the ocean. When they got out, they played on the beach as the ocean water evaporated from their bodies. Ava wondered if adding salt to the water affects how quickly water evaporates.

When Ava got home, she set up nine glasses with one cup of tap water in each glass. She added four tablespoons of salt to each of three glasses and two tablespoons of salt to each of the other glasses. She added no salt to the final three glasses. Every day for one week, she measured the amount of water left in each glass.

In this experiment, the glass with two tablespoons of salt were part of ___.

• an experimental group

• a control group

Multiple Select

Spencer was baking cupcakes for his stepfather’s birthday. Spencer wondered whether the volume of a cupcake would be affected by the type of flour in the batter.

Spencer bought three types of flour and made three batches of cupcakes. He followed the same recipe for each batch, except for the type of flour used. He made one batch using whole wheat flour, one batch using cake flour, and one batch using buckwheat flour. After all the batched had baked and cooled, Spencer measured the dimensions of each cupcake to calculate its volume.

In this experiment, the volume of cupcake was __.

• independent variable

• dependent variable

Multiple Select

Tilda’s brother thought that crushed ice would keep his soda cooler than whole ice cubes.

To test this idea, Tilda divided a large bottle of soda equally among six glasses. Tilda added five whole ice cubes to each of the first three glasses while her brother crushed five ice cubes into small pieces before adding them to each of the other three glasses. Ten minutes after all the ice had been added to the glasses, Tilda used a thermometer to measure the temperature of the soda in each glass.

Which of the following was an independent variable in this experiment?

• Spencer wondered whether the volume of a cupcake would be affected by the type of flour in the batter.

• the size of the ice pieces

Fill in the Blanks

Multiple Choice

Observe the picture, there are strawberry and chocolate flavors of ice cream. This is _.

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• qualitative data

• quantitative data