Physical Science and You Chapter One: Studying Physics and Chemistry Chapter Two: Experiments and Variables Chapter Three: Key Concepts in Physical Science

Chapter Two: Experiments and Variables 2.1 Variables and Relationships 2.2 Experiments and Data

Investigation 2B Why are graphs useful? Making Predictions from a Graph

2.2 Experiments and Data An experiment is a situation specially set up to investigate the relationships between specific variables. Experiments test whether or not a hypothesis has scientific support.

2.2 Experiments and Data An experiment is a situation specially set up to investigate the relationships between specific variables. Experiments test whether or not a hypothesis has scientific evidence or support.

2.2 Converting between units If experiments can not be performed, then a theory can be tested by comparing predictions of the theory with observations of what occurs in nature. Several different theories of how solar systems form are currently under scientific review.

2.2 Experiments and Data The first step in designing a good experiment is to clearly state what is to be tested (make a hypothesis). The next part, called the procedure, tests the hypothesis using good experimental design. In many experiments data in the form of values or measurements is the scientific evidence. Scientists analyze the data by thinking, graphing, or doing calculations. If the experiment is successful, the analysis will lead to a conclusion, which is usually a statement about the hypothesis.

2.2 Controlled Experiments In a controlled experiment only one variable is changed at a time.

2.2 Other Experiments In some tests you may be asked to identify the experimental variable by looking at data collected in an experiment.

2.2 Error Error is the difference between a measurement and the true value of what is measured. Which of these values is has the LEAST amount of error? Which value has the MOST error?

2.2 Accuracy In science, the word accuracy means how close a measurement is to the true value of what is being measured. Which of these values is the MOST accurate?

2.2 Averages When you make many measurements of the same thing you will notice that the values cluster around an average. To calculate an average, add up all the measurements and divide by the total number of measurements. Some measurements are more than the average and some are less. How are averages useful?

2.2 Estimating Error In science, two measurements are considered the same if their difference is less than or equal to the amount of error.

2.2 Reproducibility Reproducibility means two things in science experiments: 1.If you repeat the experiment the same way, you always get the same result. 2.Others who repeat your experiment get the same result. Is the data from these two groups reproducible? Why or why not?

2.2 Drawing Conclusions The point of experiments is to produce data that allows scientists to come to conclusions. Which group’s data gives a more valid conclusion about the hypothesis?

Health Connection Ads sometimes influence us through the power of suggestion. We recognize the name of the product. We may not be sure why but we buy the product. Testing the Power of Suggestion