CHARACTERISTICS OF SCIENCE by hcj

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									CHARACTERISTICS OF SCIENCE Science Review
These standards are integrated across the five content domains. Be sure to review the following: 1. Apply skills used in explaining and understanding the characteristics of science including comprehension, application, synthesis, evaluation, and weighing of evidence. a. Examine new experiments that may reinforce or alter scientific understandings and suggest alternate explanations of scientific evidence. b. Apply knowledge of safety practices and identify appropriate laboratory techniques for a given situation. c. Choose procedures for investigation of scientific problems. d. Compare and analyze data using graphs and tables. e. Determine reasonable conclusions based on presented data. f. Evaluate reasonableness of conclusions after considering research methods and other scientific knowledge. g. Determine the most appropriate method for recording and analyzing data. h. Solve scientific problems by substituting values into formulas, using dimensional analysis, or using simple algebra. i. Evaluate written reports of laboratory findings, scientific accounts, and supporting data. j. Determine appropriate data to support scientific claims. k. Recognize that scientific principles are universally applicable, discovered through experiment or observation, and subject to change. l. Understand the necessity of continuously evaluating current theories. m. Recognize that new hypotheses often require new experiments. n. Comprehend the importance of controls in scientific experiments. o. Explain why estimated and calculated answers to numerical problems may differ. p. Evaluate the effects of possible measurement errors in calculations.

Become familiar with the following terms: Research problem Hypothesis Dependent variable Independent variable Variable Experimental group

Control group Conclusion Accuracy Prediction Hypothesis Data

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THE SCIENTIFIC METHOD
Science is NOT just a body of knowledge; it is also something that people do to find out about the world around them. Science involves observing the world and its events. Scientists seek facts – try to solve deeper mysteries Scientific Method: Science is investigated by a logical process, sometimes called the scientific method. This requires searching for an answer in an orderly, systematic manner. There is not one order for the six steps, but it should be done logically. 1. State the Problem Being curious; having questions about what you observe 2. Analyze the Problem (research the problem) Gathering information; look for patterns; look at what other research has done 3. Form a hypothesis Hypothesis: educated guess on what you think will happen 4. Test the hypothesis through experimentation Experimentation; make sure you have a control and a variable; test multiple times. 5. Record and analyze data Look at your data; look for patterns 6. Form a conclusion Was your hypothesis true?; no theory can become fact until it has been tested under all possible conditions; Your hypothesis is not always true.

Sometimes, you can make a prediction about what will happen. This is an educated guess based on past experience. You can also make an inference. An inference is an implied answer based on indirect observations. For instance, you might record that it rained today if you went outside after school and saw puddles on the sidewalk, but you never actually saw it rain. The Research Problem Once the problem has been stated, the problem must be investigated. This is done through research. The scientist searches the literature published on the problem, interviews potential experts, and searches the Internet to find all the information available. The problem must be restated so that only one variable is tested. Variables are the specific factors that can be measured. The independent variable (manipulated variable) is a set of conditions that will be changed by the researcher. The dependent variable (responding variable) is the set of conditions that may or may not change as the independent variable is changed. The dependent variable is the variable being tested. The group of samples or subjects that is tested by changing a variable is the experimental group. Another set of samples or subjects makes up the control group. This group is EXACTLY like the experimental group, except that no variable has been changed. The purpose of the control group is to verify whether or not changes occurred in the experimental group and whether or not the changes were a result of the independent variable.

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The anticipated results are stated at the beginning of the experiment in the form of the hypothesis. Sample Research Problem 1 A student wishes to test the rate of photosynthesis in plants at different temperatures. Elodea plants will be tested at different temperatures and the rate of oxygen (O2) production will be measured. Research Problem: Does temperature affect the rate of oxygen production in Elodea?

Independent Variable: ___________________________________ Dependent Variable: Experimental group: Control group: Hypothesis: ___________________________________ Set of plants ___________________________________ Set of plants ___________________________________ Increase in temperature will increase the rate of O2 production

Sample Research Problem 2 A student wishes to find out if eating breakfast has any effect on reaction time. Research Problem: Does eating breakfast affect reaction time of high school students? Independent Variable: ____________________________ Dependent Variable: Experimental group: Control group: Hypothesis: ____________________________ Students who ______________________________________ Students who ______________________________________ Students who ______________________________________

Practice Section - Read the following and answer the questions that follow. A. Mrs. Brim wants to find out why seawater freezes at a lower temperature than fresh water. B. Mrs. Brim goes to the media center and reads a number of articles about the physical properties of solutions. She also reads about the composition of seawater. C. She also travels to a nearby beach and observes the conditions there. D. After considering all this information, Mrs. Brim sits at a desk and writes, My guess is that sea water freezes at a lower temperature than fresh water because sea water has salt in it. E. She goes to her classroom lab and does the following: 1. Fills each of two beakers with 1 liter of fresh water. 2. Dissolves 35 grams of table salt into one of the beakers. 3. Places both beakers in a refrigerator whose temperature is -1°C. 4. Leave the beakers in the refrigerator for 24 hours. F. After 24 hours, Mrs. Brim takes the beakers out of the refrigerator and looks at them. She finds that the fresh water beaker is frozen and the salt water is still liquid.

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G. She writes in her notebook, It appears as if the salt water freezes at a lower temperature than fresh water does. H. She continues, “Therefore, the reason seawater freezes at a lower temperature is that sea water contains dissolved salts while fresh water does not. Which statement contains the CONCLUSION? Which statement refers to GATHERING INFORMATION? Which statement contains the HYPOTHESIS? Which statement contains the TEST OF THE HYPOTHESIS? In which statement is the PROBLEM defined? Which statement contains the DATA in the experiment? _________
___________ ___________ ___________ ___________ ___________

EXPERIMENTAL ERROR Sometimes, it is helpful to determine if there is error associated with your experiment. Sources of error can come from not doing the lab well (poor laboratory technique), improper experimental set-up, and errors in data collection. You may be asked to determine sources of error on the graduation test. Think of anyway that the experiment could have been done wrong and this will lead to a source of error. ANALYZING, EVALUATING, AND PRESENTING INFORMATION During the experiment, data and observations are recorded in a logbook. This data then is analyzed in a variety of ways: data tables, graphs, etc. You must be able to read a data table or graph and determine what it is trying to say. The analysis of the data is summarized in a conclusion. The conclusion will state whether the hypothesis was supported or rejected. The experiment should be repeated multiple times to verify the accuracy of the data before stating the conclusion.

SAFETY EQUIPMENT AND RULES Be familiar with the following safety rules for working in a laboratory: 1. Always wear goggles when working with flames or chemicals. This includes acids. 2. Never smell a chemical directly under your nose. Wave the odor from the bottle or beaker towards your nose (called “wafting”). Remember that leaving a cap off of a smelly chemical can cause the chemical’s smell to spread throughout the room in a process called diffusion. 3. Be sure to use tongs to handle hot equipment. Use the back of your hand held close to the item to determine if it is too hot.
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4. When heating chemicals, make sure to point to opening of the test tube away from you and your partner. 5. When lighting a Bunsen burner, light the match and then turn on the gas. 6. Know the location of the fire extinguisher, eyewash, first aid kit, and emergency shower. 7. Be sure to read all directions before starting an experiment. 8. Report all spills and accidents to your teacher immediately. Safety goggles should be worn at all times in the lab. It is the single most important safety device. The fire extinguisher should be an ABC or BC type fire extinguisher.

PRESENTING DATA The following are examples of ways to present data. Look at the following and answer the questions that follow. Bar Graph - shows how subjects compare in relation to the main topic.
Growth of Pea Plants 60cm 50cm 40cm 30cm 20cm 10cm 1 2 3 4 5 6 Weeks plant has been growing

1. What information is given in this graph?

2. What week shows the highest growth rate?

3. What is the maximum height of the plant?

Line Graph - is effective in showing trends, changes over time
Plant Height over 6 weeks 30cm 25cm 20cm 15cm 10cm 5cm 1 2 3 4 5 6 Weeks plant has been growing

4. How tall was the plant the second week?

5. What period of time shows the greatest growth?

6. If the growth continues at this rate, can you estimate the height of the plant in the 7th week?

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Circle Graph - shows how parts relate to a whole (percentages) 7. What is the total percent of a circle graph?

8.

Why would a circle graph not measure the growth of a plant?

Nitrogen and Oxygen 78%

9. If you have 500mL of atmosphere, how many mL of nitrogen and oxygen are there?

PROCESS SKILL PRACTICE
Analyzing an Experiment Do Plants like Coca Cola? Hypothesis: If ten plants are given Coca Cola and ten plants are given water, the plants fed Coca Cola will be taller and have more leaves. 1. Independent variable: 2. Dependent Variable: __________________________________ __________________________________

Experimental Set-up Water
X X X X X X X X X X X = individual plant

Coca Cola
X X X X X X X X X X

3. Which group is the control?

4. Why have a control group?

Name at least three factors that will be the same for both sets of plants.

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Analyzing a Line Graph Look at the graph and answer the questions below.

Beaker of Water Placed in the Freezer
70 60 50 40 30 20 10 0 -10 -20 -30 0 20 40 60 80 100 Time in Minutes

1. About what temperature is the water after 20 minutes has passed? a. 50C b. 43C c. 35C d. 24C e. 15C 2. How long does it take for the beaker of water to reach a temperature of 0C a. 10 minutes c. 40 minutes e. 70 minutes b. 30 minutes d. 50 minutes 3. After the beaker has been in the freezer for 70 minutes, its contents would most probably be a. all water at a temperature slightly above 0C b. all water at a temperature slightly below C. c. partly water and partly ice, all at a temperature of 0C. d. all ice at a temperature of 0C. e. all ice at a temperature slightly above 0C.

4. What happens to the temperature from 50-70 minutes? a. The temperature increases b. The temperature decreases c. The temperature does not change d. This information cannot be determined from this graph.

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Temperature in Celsius

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Interpreting a Data Table DATA ON THE PLANETS Temperature K Night Day 13 683 233 275 170 123 103 103 103 43 720 295 300 313 223 123 123 63 Surface Pressure (atm) 1000 15 0 0.006 10000 1000 2 7 unknown Radius Earth radii 0.3819 0.9500 1.000 0.5306 10.949 9.1377 3.6837 3.5654 0.8946 Density Earth Density 0.9554 0.9524 1.000 0.7188 0.2422 0.1246 0.2905 0.3790 0.2523

Planet Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto

1. Which planet has the hottest temperature at night?

____________________

2. Which planet is nearest earth in density?

____________________

3. What are the radii of all the planets compared to?

____________________

5. List the planets in order of surface pressure with the greatest pressure first and the lowest pressure last.

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Interpreting a Circle Graph Below is a circle graph. The title of this graph is “Earth’s Surface.” Each segment has a name and a percent value. Look at this graph, you can see that the pacific ocean covers 33% of the Earth’s surface. THE EARTH’S SURFACE

Indian Ocean 14% Land 29%

Atlantic Ocean 16%

Artic ocean 3% Other Seas 5% Pacific ocean 33%

Try finding the following details on the graph above. 1. What percent of the Earth’s surface is land? ___________________ 2. What total percent of the Earth’s surface is covered by the two largest oceans? ______________________ 3. What total percent of the Earth’s surface is covered by water? ______________ 4. By comparing the amount of surface covered by water with the amount of surface covered by land, what would you say would be the key point made by this circle graph?

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