Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Section 2 Scientific Methods Chapter 1 Bellringer Complete these two tasks: 1. Describe an advertisement that cites research results. 2. Answer this question: Why is it important for scientists to write reports about their findings? Write your answers in your science journal.

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 What You Will Learn Scientists ask questions, make observations, form hypotheses, test hypotheses, analyze results, and draw conclusions. Scientists communicate their steps and results from investigations in written reports and oral presentations. Section 2 Scientific Methods

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 What are Scientific Methods? Scientific Methods are the ways in which scientists follow steps to answer questions and solve problems. All life scientists share a curiosity about the natural world and similar methods to investigate it. Scientists may use the same steps in their investigations, but not always in the same order. Section 2 Scientific Methods

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Section 2 Scientific Methods Chapter 1

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 Ask a Question An observation may be hard to explain or out of the ordinary. Such an observation can lead to a question. Looking for answers may lead to more observations and more questions. Section 2 Scientific Methods

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 Make Observations Observations must be made with great care and attention to details. Observations are only useful if they are accurately made and recorded. Records of observations include measurements, tables, photographs, and written descriptions. Section 2 Scientific Methods

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 Make Observations, continued Any information gathered through the senses is an observation. Some typical observations include measurements of length, volume, time, speed, or temperature. Observations can describe the color, shape, or behavior of an organism. Section 2 Scientific Methods

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 Form a Hypothesis After asking questions and making observations, scientists may form a hypothesis. Sometimes observations lead to several hypotheses. A hypothesis is a possible explanation or answer to a question. A hypothesis needs to be testable. Section 2 Scientific Methods

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 Form a Hypothesis, continued After forming a hypothesis, a scientist usually makes a prediction. The prediction is usually stated in an if-then format. The prediction is used to set up an experiment to test the hypothesis. Section 2 Scientific Methods

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 Test the Hypothesis Scientists conduct controlled experiments to test their hypotheses. A controlled experiment tests only one factor at a time and consists of a control group and one or more experimental groups. A factor is anything in an experiment that can influence the experiment’s outcome. Section 2 Scientific Methods

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 In a controlled experiment, every factor must be kept the same except for the one factor being tested. The one factor that is tested, or changed, in an experiment is called the variable. Section 2 Scientific Methods Test the Hypothesis, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 The group of test subjects that includes the variable is called the experimental group. The group that does not change is called the control group. The only difference between the control group and the experimental group is the variable being tested. Section 2 Scientific Methods Test the Hypothesis, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 Section 2 Scientific Methods Test the Hypothesis, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu The Nature of Life Science Controlled Experiments and Variable Chapter 1

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 In addition to carefully controlled factors, a good experiment should test many individuals. When scientists test many individuals, and repeat the experiment several times, the results are more certain. Section 2 Scientific Methods Test the Hypothesis, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 Test the Hypothesis, continued Section 2 Scientific Methods

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 Analyze the Results After scientists finish their tests, they must analyze the results. Data are often organized into graphs or tables. This helps scientists focus on the effects of the variable being tested. Section 2 Scientific Methods

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 Draw Conclusions After scientists analyze the results, they can draw conclusions about whether the results support their hypotheses. When the results do not support the original hypothesis, scientists still learn from the experiment. A single experiment rarely answers a complex question. Each experiment builds on prior knowledge, and suggests areas of future study. Section 2 Scientific Methods

Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Chapter menu Chapter 1 Communicate Results After scientists complete an investigation, they communicate their methods, results, and conclusions. By communicating with written reports and oral presentations, scientists allow other scientists to repeat their work to see if the results are the same. Sharing information may also help other scientists with their own investigations. In this way, the scientific methods help strengthen our knowledge. Section 2 Scientific Methods