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Lesson 211Le

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Investigations and Experiments

Investigations and ExperimentsLesson 211

Science

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Published by Pace Learning Systems, Inc., Tuscaloosa, Alabama. Copyright © 2015 by Pace LearningSystems, Inc. All Rights Reserved. Printed in the U.S.A. No part of this publication may be reproduced,stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical,photocopy, recording, or otherwise, without the prior written permission of the publisher.

Reading

Lesson 201, Reading Strategies: Unit 1

CR07-4201

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Science

Lesson 211 Investigations and Experiments

CSR4211

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To the Student You Should Know… What a model is (Lesson 130: Unifying Concepts and Processes) About the scientific method (Lesson 130: Unifying Concepts and Processes) How to Use This Book… In this book, you will find numbered parts that are called frames. Within these frames, you will be asked to fill in the blanks with a word or words to complete a sentence about investigations and experiments. Write your answers on a separate piece of paper. Then look at the top of the next page in the book to check your answers. The wording of your answer may vary from the answer in the lesson. Be sure to write an answer for each blank in the lesson. Words in the lesson that are followed by this symbol (*) are listed in the Glossary at the end of this lesson. The Glossary will show you what the word means. Some words appear in the lesson in boldface type. This style is used to show that the name or subject being discussed has some importance or significance in science and to the lesson. If you work through the lesson in this way, you will learn about investigations and experiments. If you do not know the subjects listed under the You Should Know… section, ask your teacher for the recommended lesson. If you do not understand how to use this book or need assistance with certain frames, ask your instructor for help. Now turn the page and begin.

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Table of Contents Section One: Setting Up Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Section Two: Bias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

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Section One: Setting Up Experiments Objectives:

• You will know how to make a hypothesis. • You will know how to operationally define variables. • You will know the difference between independent and dependent

variables. • You will know how to test a prediction. • You will know how to control for variables in an experiment. • You will know how to use experimental data to validate results.

The Scientific Method in Everyday Life

The scientific method is a process scientists use to discover new things about the way the world works. Many people think the scientific method is something that is only used in labs and research facilities, but the scientific method can be used in your everyday life to solve problems.

For instance, you may use the scientific method if you work on a car or other machine. When working on a car, you may listen to the engine and drive the car around to see what the problem seems to be. Then, you may make a guess about what is wrong and try something to see if it fixes the problem. If your repair does not fix the problem, you assume your initial guess was wrong, and you try something else. The process you used is called the scientific method!

Doctors also use the scientific method when diagnosing patients. The scientific method can also be used when analyzing sales problems, improving productivity, and determining why a sports team is losing or winning. Any time a problem needs to be solved, the scientific method can be used. You do not need to be a scientist to benefit from the scientific method; it can help you every day of your life.

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1. As you may know, scientists often do experiments* to learn more about how the world works. In this lesson, you will learn the rules you need to follow in order to conduct a good experiment.

2. When you think of a science experiment, you may picture a person in a

white coat surrounded by test tubes and high-tech equipment. Not all experiments, however, are like this. Experiments can be conducted anywhere you want to learn more about how something works. You can even conduct an experiment at home or work. Scientists use _______ to learn about how the world works.

3. If you wanted to figure out which sandpaper in your workshop made the

smoothest surface, you could do a quick _______. An experiment is a way to answer questions and figure things out. It does not have to involve expensive equipment or a lab.

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4. When scientists start to conduct an experiment, they go through a series of

steps called the scientific method*. The scientific method gives you a series of steps to follow so your _______ is more likely to be successful. You learned about the steps of the scientific method in Lesson 210: Scientific Inquiry.

5. Using the _______ helps you set up a good experiment. Let’s review the

steps of the scientific method, which are always used to conduct experiments. In this lesson, we will study the scientific method in more detail.

6. Before you can perform an experiment, you must know what it is that you

want to find out. The first step in the scientific method is to state the problem or question that you wish to answer. By stating the _______, you decide what you want to test.

7. The first step in the scientific method is to _______ the _______. 8. After you have decided what question you want your experiment to

answer, you should study information that has already been proven about the subject. When getting ready to perform an experiment, first, you state the _______. Second, you study _______.

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2. experiments 3. experiment

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9. You must study information before performing the experiment so that

you can find out what is already known about the subject. This act is also called performing research. After researching, you have a better idea of how to set up the experiment to get the most accurate results. The second step of the scientific method is to perform _______.

10. After you have learned all that you can about the problem you are

studying, you can make a guess about what might happen when you actually perform the experiment. Studying information about the problem will help you _______ about what might happen in an experiment.

11. The third step in the scientific method is to make a hypothesis*

(hy·PAH·thuh·sis). A hypothesis is an educated guess that attempts to explain why something works or behaves the way it does. A hypothesis proposes a testable explanation for observations about the world around you. A hypothesis frequently relies upon previous knowledge, facts, and general principles. For example, if you are in a toy store watching people shop, you may notice that when children are with their parents they often ask for certain toys.

You could make the following hypothesis which you could test: Shoppers

who have their children with them buy more toys than shoppers who do not have their children with them.

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4. experiment 5. scientific method 6. problem or question 7. state; problem or question 8. problem or question; research or information

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12. A(n) _______ is a statement about what you think might be true or how

you think something is supposed to work. 13. You have probably noticed that it is easier to dissolve sugar in a hot

liquid, such as coffee, than in a cold liquid, such as iced tea. From this information, you might make the following hypothesis:

The temperature of a liquid affects how easily things will _______ in it. 14. Let’s say that when you are walking through the woods, you notice that

the birds sing more in the early morning and at dusk than they do during the day. You make the following hypothesis:

Since early morning and dusk are not as bright as midday, birds _______

more when there is less _______. 15. Here is another example. You are building a table, and you notice that

when you cut wood across the grain, it tends to chip. When you cut wood with the grain, it does not chip as much. From these observations you could make the following hypothesis:

Wood _______ less when it is cut _______ the grain.

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9. research 10. guess

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16. A(n) _______ is an educated guess about how things around you work.

Sometimes, you make a hypothesis because you notice something happening and want to test it out; other times, you simply want to make a guess about how something might work.

17. If you were walking along a river and noticed little mounds of dirt in

some sections and no mounds of dirt in other sections, you might make a(n) _______ about what the mounds were and what had made them.

Here are some different hypotheses you could make:

• The mounds were made by an animal. • The mounds occur where the ground is very wet. • The mounds were made by people who live near those sections of the

river. 18. As you can see from frame 17, you can make more than _______

hypothesis about something. A hypothesis is simply a guess that something might be _______.

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12. hypothesis 13. dissolve 14. sing; light 15. chips; with

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19. When you want to understand the world better or when you want to find

out why something is happening, you perform an experiment. Before you can actually perform the experiment, you must guess what might happen, or make a(n) _______. This is the third step in the scientific _______.

20. Read the passage below: You are in a restaurant, and there is a blue light at one end of the dining

room. Every time the blue light comes on, a waitress goes into the kitchen and comes back out with food.

Make a hypothesis about what the blue light means. _______ 21. Making a hypothesis is only one step in the _______. Since a hypothesis is

only an educated guess, you will need to make a more specific prediction* to test whether the hypothesis is true or false. A prediction is an educated guess that is more specific than a hypothesis. It tells exactly what you think the outcome of the experiment will be.

22. After making a hypothesis, you make a more specific _______.

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16. hypothesis 17. hypothesis 18. one; true

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23. A prediction is even more specific than a hypothesis. A prediction is

something you can test to see if you are right. For example, if “People buy more in a toy store when they have their children with them” is your hypothesis, you could make the following prediction:

People in the store over the age of 18 who have children with them will

average a higher check-out receipt than people over the age of 18 who do not have children with them.

The prediction tells you exactly what you are going to measure: the

amount of money spent. 24. If you had the hypothesis “The temperature of a liquid affects how easily

you can dissolve something in it,” you would need to make a more specific guess about the outcome or a(n) _______. Furthermore, your prediction would need to define exactly what you want to measure. Your prediction would define exactly what substances you would test in your experiment.

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19. hypothesis; method 20. The blue light means food is ready to be picked up by a

waitress. 21. scientific method 22. prediction

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25. The following prediction could be made from the hypothesis in frame 24: The time it takes for 1 teaspoon of sugar to dissolve in 200 degree water

will be less than the time it takes for 1 teaspoon of sugar to dissolve in 50 degree water.

This prediction is more _______ than the hypothesis. 26. So, once you have made a hypothesis, you then must make a very specific

prediction. The prediction must be testable. For example, if you predicted that “Water with salt dissolved in it will boil at a higher temperature than pure water,” you could perform an experiment to test whether your prediction was true or not.

27. If you predicted that the sun will be at half its current brightness in 1

million years, you could not _______ it because you could not possibly be here in one million years!

28. When using the scientific method, you first ask a(n) _______ or state a(n)

_______. Next, you study _______. Then, you make a(n) _______. After making a hypothesis, you should make a more specific _______. You must be sure that your prediction is _______.

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24. prediction

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29. Your prediction must not only be testable, but also all of the words in your

prediction must be operationally defined. When a word is _______ defined, it is defined in a way that means the same thing to everyone. For instance, look back to frame 26. If you were testing that prediction, you would understand that the phrase higher temperature would mean a temperature greater than 100 degrees Celsius, which is the temperature when pure water boils. You would understand exactly what the terminology means.

30. An operational definition* specifies the mathematical operations you

carry out to measure something so that the word means _______ (the same / a different) thing to everyone. This permits others to precisely understand your results. It also allows others to repeat the experiment themselves in order to confirm or disprove your findings.

31. If you predicted that something would increase people’s level of stress,

you would need to operationally define the word _______. 32. One way to operationally define the word “stress” would be to say that

“stress” will be measured by measuring a person’s blood pressure, with readings over a certain value indicating _______.

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25. specific 27. test 28. question; problem; information; hypothesis; prediction; testable

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33. An operational definition explains exactly what you mean when you use a

certain word. Look at the prediction below, and write down the words that need to be operationally defined.

Plants that are pollinated by bees grow larger than plants pollinated by

tiny insects. _______ and _______ 34. Look at the prediction below, and write down the words that need to be

operationally defined. When there are a lot of older trees in an area, Indigo Buntings (a kind of

bird) will not live there. _______ and _______ 35. Great work! Now you know that a prediction must be _______ and all the

terms in it must be _______. 36. Read the hypothesis below, and make a specific prediction based on it. Delivery-truck drivers would be more careful drivers if they were fired

after having just one accident. _______

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29. operationally 30. the same 31. stress 32. stress

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37. If you performed an experiment to see if the hypothesis in frame 36 was

true, you could compare two different groups of delivery truck drivers—those who would get fired after one accident and those who do not get fired after one accident.

In most experiments, you compare two or more groups. You usually

predict that one group will act differently in some way from the other. You also are usually measuring something—such as how much salt will dissolve, or the score on a test. There are two other very important terms to use when talking about experiments. A variable* is a factor that is changed or tested in some way. There are two different types of variables in each experiment: dependent variables and independent variables.

38. A dependent variable* is what you are measuring. The results of an

experiment depend on the value of the dependent variable. If you are measuring how much acid you need to put in different solutions before they reach a certain level of acidity, the dependent variable is how much _______ you put in.

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33. larger; tiny 34. a lot; older 35. testable; operationally defined 36. The number of accidents for delivery-truck drivers who could be fired for having one will be lower than the number of accidents for other drivers.

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39. The _______ variable is what you measure. If you are measuring the speed

of runners wearing different brands of shoes, the dependent variable is _______.

40. If you are measuring how much rats eat when given two different drugs,

the dependent variable is the _______ of food. 41. In an experiment, whatever you measure is the _______. An experiment

can only have one dependent variable at a time. 42. If you have two different metals and you are measuring how much force it

takes to scratch them, the dependent variable is the force necessary to _______ them.

43. There is another type of variable in each experiment, too. The independent

variable* is the one thing that is different between the two groups. For example, if you have two groups of people—one group is over 40 years old, the other group is 40 or under—and you are measuring how well they remember things, the dependent variable is _______. The independent variable is age, because age is the only thing that is different between the two groups.

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38. acid

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44. If you are comparing the growth rates of two different plants, the

independent variable is the type of _______. 45. A scientist has two species of birds in his lab. He is measuring how loud

each species sings. The dependent variable is _______; the independent variable is _______.

46. A scientist is measuring how much force it takes to crack a 10 cm sphere

versus a 2 cm sphere. The independent variable, or the thing that makes the two groups different, is _______. The dependent variable is _______.

47. The _______ is what you measure. The _______ is what makes the two

groups different.

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39. dependent; speed 40. amount 41. dependent variable 42. scratch 43. how well they remember or memory

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48. Once you have made your prediction, operationally defined your

variables, and identified the independent and dependent variables, you are ready to conduct your experiment. When you conduct an experiment, you want to make sure all other variables are controlled, or kept the same. That includes any factors besides the independent and dependent variables.

49. Controlling all factors, or variables, in an experiment is very important.

The only variables that should be different are the one you are measuring, or the _______ variable, and the independent variable. The rest should be exactly the same, and they are said to be controlled.

50. For example, if you wanted to find out which car goes the fastest, the only

thing that should be different is the type of _______. You need to race them on the same road, on the same day, and with the same driver.

51. What if you put a slow driver in one car and a fast driver in another? It

would be impossible to know which car was the fastest. What if you raced one car on a smooth road and another on a bumpy road? The bumpy road might make one go slower. These variables would _______ (help / ruin) your experiment.

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44. plants 45. loudness; kind of birds or species of birds 46. size of the sphere; force 47. dependent variable; independent variable

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52. This is why you must control the variables in an experiment. If you use

the same driver, he will drive both cars the same way. If you use the same road, there will be nothing to slow the cars down. Therefore, you can accurately measure the speed of the cars alone. This is your _______ variable.

53. If you want to find out how quickly salt dissolves in a liquid at different

temperatures, the independent variable is _______, and the dependent variable is the time it takes to dissolve. If the liquid in one group is water and the liquid in the other group is not water, then your experiment is invalid. The only difference between the groups should be temperature.

54. When you use water for both groups, we say you control the kind of

liquid. This means you are making sure it stays the same between your two groups. If you want to measure how children affect how much their parents purchase in a toy store, you should make sure one group is not all women and the other group is not all men; in other words, you should _______ for gender. You should control for all other factors, too.

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49. dependent 50. car 51. ruin

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55. The independent variable should be the only thing that is different

between the groups. If you do not control all variables except for the independent variable, you cannot really test your prediction. If you did not control for gender in the toy store experiment, you could not be sure whether it was gender or the presence of children that affected how much was purchased.

56. The dependent variable is what you measure. The independent variable is

what you change. All other variables should be _______. If you are studying how the width of a tower affects its stability, you should control for the material the tower is made of, the height of the tower, and how the tower is attached to the ground. The only thing you want to vary is the _______.

57. Once you have controlled for all variables other than the independent

variable, you are ready to conduct the experiment. So, one step in the scientific method is to make a guess called a(n) _______. Then you make a specific _______. Then you conduct the experiment.

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52. dependent 53. temperature 54. control

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58. After making a prediction, you should collect data while performing your

experiment. Make sure you collect your data carefully. If you are unsure of a measurement, you should leave that measurement out. Never guess at data. You should always repeat the experiment if you can to make sure that your data is reliable. Your measurements should be close to the same each time you repeat the experiment. If you are measuring how long it takes salt to dissolve in water, make sure you take more than one measurement and average them.

59. If you are measuring how high a frog jumps, you should take more than

one _______. You want to make sure that you have measured and recorded the data correctly. It is also important for your measurements to be reliable in case someone else would need to use them to repeat the experiment themselves.

60. When people measure things such as time, they are usually not exactly

right. It might take more time for you to click the stopwatch than it would take someone else. It is always best to take more than one measurement and _______ them. When you do this, you make sure that you have more accurate results.

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56. controlled; width 57. hypothesis; prediction

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61. If you are measuring how many people walk by a certain store every

minute and you miss a minute, you should leave that minute _______ of your data.

62. Once you have collected your data, you should compare the results to

your prediction and hypothesis. If your prediction was right, then your hypothesis is probably right. If your prediction was wrong, then your hypothesis and the setup of your experiment may need to be modified.

63. Let’s review the scientific method again. First, you identify a(n) _______.

Next, you perform _______. Third, you state a(n) _______. Then you make a more specific _______. Next, you conduct the _______. Then collect the _______, and compare the results to your prediction.

64. In an experiment, the variable you measure is called the _______, and the

variable you change is called the _______. All other variables must be _______.

65. When you analyze your data, you should be as accurate as possible and

_______ numbers together to make sure your results are accurate. If you miss a measurement, leave it _______. Do not insert a made-up number.

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59. measurement 60. average

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