Understanding Variables in Science

What is an independent variable?

• A variable that is not relevant to the experiment.

• The variable that is measured in response to changes.

• A variable that remains constant throughout the experiment.

• An independent variable is the variable that is changed or controlled in a scientific experiment.

Answer explanation

An independent variable is the one that is changed or controlled in an experiment to test its effects on the dependent variable. This distinguishes it from other variables that may remain constant or are measured.

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NGSS.MS-PS2-2

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What is a dependent variable?

• A dependent variable is a constant factor that does not change during an experiment.

• A dependent variable is the initial condition set before the experiment begins.

• A dependent variable is the outcome variable that researchers measure in an experiment.

• A dependent variable is the variable that is manipulated by the researcher.

Answer explanation

A dependent variable is the outcome variable that researchers measure in an experiment. It changes in response to the independent variable, which is manipulated by the researcher.

In an experiment measuring plant growth, what is the independent variable?

• The temperature of the environment.

• The factor being manipulated, such as sunlight or water.

• The type of plant being tested.

• The amount of soil used in the experiment.

Answer explanation

The independent variable is the factor being manipulated in the experiment. In this case, it refers to elements like sunlight or water that are intentionally changed to observe their effect on plant growth.

In an experiment measuring the effect of sunlight on plant growth, what is the dependent variable?

• Plant growth

• Temperature of the environment

• Type of soil

• Amount of water

Answer explanation

In this experiment, the dependent variable is what you measure to see the effect of sunlight. Since the goal is to assess how sunlight influences growth, 'plant growth' is the correct choice.

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NGSS.MS-LS1-5

How do you represent data visually?

• Audio recordings

• Charts, graphs, infographics, and maps.

• Tables and spreadsheets

• Text documents

Answer explanation

Data is best represented visually through charts, graphs, infographics, and maps, as they effectively convey complex information at a glance, making it easier to understand trends and patterns compared to other formats.

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NGSS.MS-PS3-1

What type of graph is best for showing changes over time?

• Bar graph

• Scatter plot

• Line graph

• Pie chart

Answer explanation

A line graph is best for showing changes over time as it effectively displays trends and patterns by connecting data points with lines, making it easy to visualize how values fluctuate over a period.

If you increase the amount of water given to a plant, what variable are you changing?

• Amount of water

• Type of soil

• Size of the pot

• Amount of sunlight

Answer explanation

By increasing the amount of water given to a plant, you are directly changing the 'Amount of water' variable. The other options, such as type of soil, size of the pot, and amount of sunlight, remain unchanged.

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NGSS.MS-LS1-5

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What does a bar graph typically show?

• Comparison of different categories or groups.

• Trends over time.

• Distribution of a single category.

• Frequency of data points in a dataset.

Answer explanation

A bar graph is primarily used to compare different categories or groups by displaying their values as bars. This visual representation makes it easy to see differences and similarities among the categories.

In a line graph, what do the points represent?

• Data values at specific points in time or categories.

• The total number of data points.

• The average of all data points.

• The trend of data over a long period.

Answer explanation

In a line graph, the points represent data values at specific points in time or categories, showing how the data changes over time. This is why the correct choice is the first option.

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NGSS.MS-PS3-1

Why is it important to control variables in an experiment?

• It is important to control variables to ensure that the experiment tests only the effect of the independent variable.

• To increase the number of variables in the experiment.

• To ensure all variables are tested equally.

• To make the experiment more complicated.

Answer explanation

Controlling variables is crucial to isolate the independent variable's effect, ensuring that any observed changes in the dependent variable are due solely to it, thus validating the experiment's results.