The Scientific Method

Transcription

1 The Scientific Method Prelab Thoroughly explore the website Understanding Science: How Science Really Works at Answer the following five questions based on your textbook and exploration of this website. Your answers must illustrate to me that you have actually read the information in the website. You will not get full credit for this prelab if you answer the questions based on what you learned already in high school without reading the material in the website. You will be expected to turn in your answers to these questions at the beginning of lab. 1. Based on your exploration of the website Understanding Science: How Science Really Works describe what science is in 3-4 sentences. 2. Based on your exploration of this website describe in a paragraph or series of bulleted steps how science is practiced. 3. Describe in a paragraph or series of bulleted steps how you may use your knowledge of the process of science to evaluate news reports and statements. 4. Based on your exploration of this website describe in a paragraph who a scientist is. 5. Briefly describe at least two ideas you previously held about science that exploring this website has caused you to reconsider. Procedure Your professor will explain the cube puzzle to you. Please participate in and enjoy this activity. You ve solved the cube puzzle and explored the website Understanding Science: How Science Really Works. Form a group of 2 students (in other words pick a lab partner) and record your names on the lines below.

2 Read the attached handout from the course webpage concerning the scientific method and examine the four diagrams in your handout illustrating the scientific method. 1. Do all of the diagrams agree? 2. How are the diagrams similar and how do they differ? Consider the steps involved and the order of these steps. Please record your answer in the space provided below. 3. Please list the steps you believe are important in practicing science in the order you think these steps would most often be carried out and explain your answer. Consider your experience with solving the cube puzzle as well as information you gained from your reading and exploration of the website. Webster s New World dictionary defines the word reason as to think logically; draw inferences or conclusions from facts known or assumed; to think out systematically; analyze Webster s New World dictionary defines the word objective as having to do with a known object as distinguished from something existing only in the mind; real, actual, regarded as something independent of the mind; without bias or prejudice, detached; reality, and the word subjective as resulting from the feelings of the person thinking; determined by and emphasizing the ideas, thoughts, feelings; not rigidly reflecting reality; having to do the perception or conception of a thing by the mind as opposed its reality independent of the minds; incapable of being checked externally or independently by other persons

3 Discuss the following questions with your lab partner and record your conclusions in the space provided below. 1. There are many fields of science. These fields are frequently divided into categories such as the social sciences including sociology, psychology, political science and education, and the natural sciences including biology, chemistry, physics and geology. Is there a definable scientific method and should there be a ridged scientific method practiced in all of the fields of science and why or why not? 2. Is the scientific method objective or subjective reasoning? Explain your answer.

4 Scientific Observations An essential skill for any scientist is the ability to make detailed, reliable observations. Good observations lead us to ask the how and why questions of scientific investigation. As a guide, observations may contain the following elements: Quantitative observation. Use measuring instruments and record numerical measurements. Qualitative observation. Record what your senses perceive. In your description you may use comparisons. Use words as and like, e.g., The anole is green like grass. The leaf feels like sand paper. Sense of sight. What does the object look like? Describe its appearance. Provide minute details. Look for something new every time you make an observation. Sense of smell. What does the object smell like? What odors does it have? How would you describe them? Sense of touch. What does it feel like? Rough, slippery, smooth? Be specific. Don't speak in generalities. Sense of sound. What sounds does it make? Have you listened many times a day to make sure you are capturing variations in sound over time? Action. Describe the action, such as, When I place a strong acid on the substance gas bubbles are given off. Sketch. Provide a detailed sketch of all or part of whatever you are observing. In this brief activity, you will practice scientific observation by listing five different, detailed observations about the items shown to you by your instructor. Be careful not to make inferences or assumptions about these items that you have not directly observed. Item 1:

5 Item 2: Work with another set of lab partners to form a group of 4. Each set of lab partners should examine the observations made by the other set of lab partners. Look for any bias, inaccuracies, or conclusions in the observations you are examining. Record any biases etc. you see in the spaces provided below. Item 1: Item 2:

6 In what other ways could you make observations of these items besides the methods you used above? Which type of observation do you think is most likely to be biased quantitative or qualitative and why? How does what you ve observed so far in this course concerning the scientific method compare to what you learned in high school and/or in previous college courses? Your answer should illustrate to me that you have read the requested material and thought about these readings and about your experiences so far. Please record your answer in the space provided below.

7 The Scientific Method Understanding Science: How Science Really works ( There are many fields of science. The fields of science are often categorized as either social science, such as sociology, psychology, or political science, or natural science, such as biology, chemistry, geology, and physics. The practice of each of these sciences is a complex process and differs somewhat from field to field. The practice of science is often called the scientific method. Making Observations The first step in practicing many of the natural sciences is making observations. In science it is important to make careful observations and record all observations in detail. Observations may be qualitative or quantitative. Quantitative observations involve numerical values and generally result from measurements. Qualitative observations are recording what you can physically sense. It is often not possible to sense chemical or physical changes or phenomena. Chemical and physical phenomena are often detected and measured using sophisticated instruments. Measurements always involve a numerical value and a unit of measurement. Being able to make and manipulate measurements is necessary in science. It is seldom possible to know what phenomena or details are important in advance. Part of the point of making observations is to determine what is unusual. Therefore, it is important to record what you see, smell, hear, otherwise sense, or measure that is not expected as well as what is expected. It is better to record irrelevant details than to miss details. Recorded irrelevant details may be ignored later. Missed observations cannot necessarily be repeated and may cause an incorrect hypothesis to be formed or cause the phenomena of interest not to be understood at all. It is necessary to record all details because you will not remember them if you do not record them. Your results will be viewed later by other scientists who will not know about any unrecorded observations. Also reviewing recorded observations at a later time may spark ideas that may not occur to you otherwise. The practice of science is a long term process. Observations are generally made over an extended period of time by more than one scientists before hypothesis are formed. Review the observations you have made before you leave the laboratory to ensure (1) you have considered all comparative information and (2) your observations have not been contaminated by expectations or belief. When you place a strong acid on an egg white you see the color change from clear to opaque white. This is an observation. If you record that the egg cooked, you have contaminated your observation with a belief that the white color was caused by the egg being cooked. Allowing expectations or beliefs to impact your observations may lead to incorrect hypotheses and/or an inability to understand the phenomena under study.

8 Forming Hypotheses Forming a hypothesis is often the second step in the natural sciences. A hypothesis is based on previous observations made either yourself or by other scientists and therefore a hypothesis cannot be formed without a set of reliable and detailed observations and a thorough literature review. A hypothesis is a possible explanation for the observations that have been made. In forming a hypothesis trends in observations or data and relationships between observations or data are examined and causes and effects are explored. A good scientific hypothesis must be testable by an experiment(s). The hypothesis must be stated so that it can be proven true or false by an experiment(s). In other words the difference between a true and false outcome must be clearly stated in the hypothesis. A hypothesis should be stated so that it can be answered with either yes (true) or no (false). Designing Experiments The use of experiments is one of the distinguishing features of the natural sciences. Designing an experiment well is difficult and requires a great deal of knowledge frequently in a variety of fields. Often a team of scientists work together in forming hypotheses and designing experiments. In most experiments some property or factor is altered or varied in a controlled manner and the response of another property or factor is observed and recorded. The factor that is changed, such as time, is called the independent variable, and the response is called the dependent variable, because the response is influenced by or dependent on the changing variable. When the data produced is presented as a graph, the independent variable is generally the horizontal or x-axis and the dependent variable is generally the vertical or y-axis. In a well designed experiment only one factor is varied at a time. If more than one factor is allowed to vary at the same time it is not possible to draw verifiable conclusions concerning the cause of the response observed. In some experiments it is necessary to use a control in order to only change one variable at a time. Here two identical populations, such as mice, are used in the experiment. Both populations are treated identically with the exception of one factor that is varied, such as administering a known amount of a toxic compound, and the responses of both populations are measured and recorded. The population not given the toxic compound is called the control. When studying living things it is seldom possible to keep all possible or even the most important variables constant and a well designed control is almost always needed. In chemistry and physics it is often possible to keep the important variables constant and a control may not be necessary. In chemistry and physics identifying all of the important variables is most important. The number of steps in an experiment should be minimized in order to minimize error.

9 Diagrams taken from the social science literature Diagrams taken from the natural science literature