SCI 207

Introduction to Science

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 The Scientific Method

 Observations

 Variables

 Controls

 Data Analysis

 Calculations

 Data Collection

 Percent Error

 Scientific Reasoning

 Writing a Lab Report

Socrates (469 B.C. - 399 B.C.), Plato (427 B.C. - 347 B.C.), and Aristotle (384

B.C. - 322 B.C.) are among the most famous of the Greek philosophers

(Figure 1). Plato was a student of Socrates, and Aristotle was a student of Pla-

to. These three philosophers are considered to be the greatest thinkers of

their time.

Aristotle’s views on science profoundly shaped medieval academics, and his

influence extended into the Renaissance (14 th - 16

th century). His opinions

were the authority on science well into the 1300s. Unfortunately, the philoso-

pher’s method was logical thinking and did not involve making direct observa-

tions on the natural world. As a result, many of Aristotle’s opinions were incor-

rect. Although he was extremely intelligent, he used a method for determining

the nature of science that was insufficient for the task. For example, in Aris-

totle’s opinion, men were bigger than women. Therefore, he made the de-

duction that men would have more teeth than women. It is assumed that he

never actually looked into the mouths of both men and women and counted

their teeth. If he had, he would have found that males and females have ex-

actly the same number of teeth (Figure 2).

In the 16 th

and 17 th centuries, innovative thinkers began developing a new

way to investigate the world around them. They were developing a method

that relied upon making observations of phenomena and trying to explain

why that phenomena occurred. From these techniques, the scientific method

was born. The scientific method is a process of investigation that involves

Figure 1: Neoclassical statue

of ancient Greek philosopher,

Plato, in front of the Academy

of Athens in Greece.

Figure 2: Humans—male and

female—have 20 baby teeth

and 32 permanent teeth.

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experimentation and observation to acquire new knowledge, solve problems, and answer questions. Scien-

tists eventually perfected the methods and reduced it to a series of steps (Figure 3).

Today, the scientific method is used as a systematic approach to solving problems. Science begins with ob-

servations. Once enough observations or results from preliminary library or experimental research have been

collected, a hypothesis can be constructed. Experiments then either verify or disprove the hypothesis. If

enough evidence can support a hypothesis, the hypothesis can become a theory, or proven fact. Theories

can be further refined by other hypotheses and experimentation. An example of this is how we further refine

our knowledge of germ theory by learning about specific pathogens. A scientific law is a summary of obser-

vations in which there are no current exceptions using the most recent technology. It can be a general state-

ment, like the Law of Gravity (what goes up must come down), or a mathematical relationship, like Newton’s

Law (F = ma). Scientific laws can be broken and theories can be proven wrong as technology improves and

provides results that are exceptions to them.

The scientific method attempts to minimize the influence of bias or prejudice in the person conducting the ex-

periment. It is human nature to have some sort of bias, and even the best-intentioned scientists can’t escape

bias. However, in the fields of science where results have to be reviewed and duplicated, bias must be avoid-

ed at all costs. The scientific method provides an objective (non-biased), standardized (easily duplicated) ap-

proach to conducting experiments. Throughout this lab you will access a series of four videos. These

videos describe the steps of the scientific method and will provide the content necessary to answer

the post-lab questions. To further understand the scientific method, let’s take a closer look at what each of

the steps entails. Please click on the link below to watch the video, gain a better understand the scien-

tific method, and answer the post-lab questions.

Video 1: https://www.esciencelabs.com/sites/default/files/Zaption/Ashford_01.mp4

Figure 3: A scientific investigation begins with an observation.

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The first step in the scientific method is observation. This step often comes naturally by watching things going

on around the world, noticing different trends, and developing questions when something is confusing. Keep

in mind that scientists don’t just use their eyes to form an observation. Instead, they use all of their senses to

completely observe something. The more you pay attention to your surroundings, the more you will begin to

think like a scientist. Note that your observations don’t have to be oriented around typical “science” things. For

instance, scientific observations don’t have to be about textbook chemicals or reactions—they can be about

the environment, cooking, people, etc.

Gathering as much information as you can on your topic of interest is important because you may discover

that someone has already performed an experiment on your observation. In addition, the more information

you have on your observation of interest, the easier it will be to make a well-informed and educated prediction

regarding what you think might happen during your experiment.

Based on your observation(s), a question can be developed. Keep in mind that not every question is a

“good” question to test with the scientific method. In this lab, we will focus on “testable” questions, or ques-

tions that can be used to construct experiments. These are questions that can be answered by doing a labor-

atory investigation. They are not opinion questions or questions that can be answered by doing research in a

book or on the internet.

Developing a good question is important because it gives your experiment direction and informs others of

what questions you are trying to answer in your experiment. It must be clear. A question such as “How do stu-

dents learn best?” is not clear because there are many different ways to test it. A better question might be “Do

students learn better before or after sleeping?” because it only tests one particular variable. Keep in mind that

you must be able to measure the results in some way for it to be considered a testable question.

A hypothesis is a type of prediction that forecasts (predicts) how changing one part of an experiment will af-

fect the results. It is not a guess. It is an informed and well-thought out prediction based upon your back-

ground research. Many times, a hypothesis is best written in the “If _________, then ________” format. The

blank space after the “if” describes the independent variable (e.g., the experimental component that scientists

intentionally manipulate and control). The blank space after the “then” describes the dependent variable (e.g.,

the predicted result of the change). Please click on the link below to watch the video, learn more about the

initial steps of the scientific method and answer the post-lab questions.

Video 2: https://www.esciencelabs.com/sites/default/files/Zaption/Ashford_02.mp4

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After you have created a question, scientists construct a hy-

pothesis. However, in order to do this, the experimental varia-

bles must first be determined. Variables are conditions that

could affect the outcome of an experiment. Think about all of

the different things that might affect how well a student performs

on a test. The amount of sleep, how long they studied, how well

they paid attention in class, if they are feeling well could affect

how well they perform.

Successful experiments incorporate as few variables as possi-

ble. However, you will always have three types of variables

(Figure 4):

 Independent Variables

 Dependent Variables

 Controlled Variables

The independent variable is what you change in an experi-

ment. Conversely, the dependent variable is what you meas-

ure in an experiment (e.g., the results) (Figure 4). There is also

a variable called the controlled variable. This accounts for the

condition (or conditions) that must remain constant in an experi-

ment. Experiments require controlled variables so that you can

determine if the independent variable actually caused the result or if it was something else. In a perfect world,

all of the variables would be controlled except for the independent variables. This can be difficult to achieve

but is a very important goal.

The procedure step is the writing of the materials used and the steps followed when conducting an investiga-

tion. The materials list must be complete and the steps to follow must be understandable so the activity can

be repeated. Other scientists should be able to look at your procedure , perform the same steps, and get the

same results without you telling them anything or giving them any clues. Procedures are best written as a

numbered sequence. It is during the procedure step that an experiment will be conducted to test the hypothe-

sis. The experiment must be unbiased in nature, meaning that the scientist cannot create an experiment that

will favor the outcome that they have predicted in their hypothesis. Please click on the link below to watch the

video, learn more about testing your hypothesis and answer the post-lab questions.

Video 3: https://www.esciencelabs.com/sites/default/files/Zaption/Ashford_03.mp4

Figure 4: Suppose you saw a change in your

dependent variable. How do you know that

change was caused by your independent

variable? You couldn’t be sure unless you

had a control. The purpose of holding the

control constant is to observe if your inde-

pendent variable actually caused a change

in your dependent variable.

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Data collection is the process of gathering and measuring information on variables in an established, sys-

tematic fashion that enables you to answer the hypothesis. Regardless of the experiment, accurate data col-

lection is essential to maintaining the integrity of the lab. Accurate means “capable of providing a correct

reading or measurement.” In science, a measurement is accurate if it correctly reflects the size of the thing

being measured. On the other hand, precise means that an experiment is repeatable, reliable, and gets the

same measurement each time (Figure 5). We can never obtain a perfect measurement. The best we can do

is to come as close as possible within the limitations of the measuring instruments.

Once you have collected your data in the most accurate and precise way, the next step is to communicate

your data. A highly effective method for communicating your data is to visually display your results. Common

ways of doing this are to create a table or a graph.

A table is a well-organized summary of data. Tables should display any information relevant to the hypothe-

sis. Table 1 displays data collected to test a hypothesis about plant growth with or without added nutrients.

Tables should include a clearly stated title, labeled columns and rows, and measurement units.

A graph is a visual representation of the relationship between the independent and dependent variable.

Graphs help to identify trends and illustrate findings (Figures 6 and 7). Here are some of the rules to remem-

ber when graphing:

Figure 5: Left: Accurate results all hit the bulls-eye on a target. Right: Precise re-

sults may not hit the bulls-eye, but they all hit the same region.

Variable Height Wk. 1 (mm) Height Wk. 2 (mm) Height Wk. 3 (mm) Height Wk. 4 (mm)

Control

(without nutrients) 3.4 3.6 3.7 4.0

Independent

(with nutrients) 3.5 3.7 4.1 4.6

Table 1: Plant Growth With and Without Added Nutrients

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 The independent variable is always graphed on the x-axis (horizontal), with the dependent variable on

the y-axis (vertical).

 Use appropriate numerical spacing when plotting the graph, with the lower numbers starting in the

lower and left hand corners of both axes.

 Always use uniform or logarithmic intervals. For example, if you begin by numbering 0, 10, 20, do not

jump to 25 and then 32.

 Title the graph and both the x- and y-axes with a unit and label such that they correspond to the data

table from which they come. For example, if you titled your table “Top Speed of Different Car Models,”

the graph title should reference this information as well.

Did you know that there are codes of ethics in scientific research, even for students?

Some of these principles are:

 Honesty: Do not fabricate, falsify, or misrepresent data

 Objectivity: Strive to avoid bias in experimental design, data analysis, and data in-

terpretation

 Carefulness: Avoid careless errors and negligence. Carefully and critically examine

your own work

Figure 6: Sample bar graph. Bar graphs are best for demonstrating comparisons be-

tween categories or trial events.

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Figure 7: Sample line graph. Line graphs are best used to show how changes occur for

a variable over time.

Scientists draw conclusions by examining the data from the experiment. There are basically two possible

outcomes. Either the experiment supported the hypothesis and it can be regarded as true, or the experiment

disproved the hypothesis (Figure 8). If the hypothesis is false, it is always recommended that you repeat the

steps in the scientific method and make adjustments to your hypothesis. If the hypothesis turns out to be

false, there are some questions to ask to find out why:

 What was wrong with the original hypothesis?

 Did you make poor observations?

 Was your experiment flawed?

Please click on the link below to watch the video, gain a better understand how to

interpret your results and answer the post-lab questions.

Video 4: https://www.esciencelabs.com/sites/default/files/Zaption/

Ashford_04.mp4 Figure 8: Scientists docu-

ment in pen and date all of

their work to maintain the

integrity of their results as

well as to help ensure repro-

ducibility.

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Lab Report

Section Purpose

Title A short statement summarizing the topic.

Abstract A brief summary of the methods, results and conclusions. It should not exceed 200

words and should be the last part written.

Introduction

An overview of why the experiment was conducted. It should include:

 Background - Provide an overview of what is already known and what questions

remain unresolved. Be sure the reader is given enough information to know why

and how the experiment was performed.

 Objective - Explain the purpose of the experiment (i.e. "I want to determine if tak-

ing baby aspirin every day prevents second heart attacks.")

 Hypothesis - This is your "prediction" as to what will happen when you do the ex-

periment.

Materials and Meth-

ods

A detailed (step-by-step) description of what was used to conduct the experiment and

how it was done. The description should be exact enough that someone reading the

report can replicate the experiment.

Results

Data and observations obtained during the experiment. This section should be clear

and concise. Tables and graphs are often appropriate in this section. Interpretations

should not be included here.

Discussion

Data analysis, interpretations, and experimental conclusions.

 Discuss the meaning of your findings. Look for common themes, relationships,

and points that perhaps generate more questions.

 When appropriate, discuss outside factors (e.g. temperature, time of day, etc.) that

may have played a role in the experiment.

 Identify what could be done to control for these factors in future experiments.

Conclusion A short, concise summary that states what has been learned.

References

You should reference any articles, books, magazines, interviews, newspapers, etc.

that were used to support your background, experimental protocols, discussions and

conclusions. Your references should be written in the APA format. The following web

site is a helpful citation maker http://www.citationmachine.net/apa/cite-a-book

Table 2: Components of a Lab Report

A scientist’s experiment is often communicated through a lab report. Table 2 outlines each component of a

lab report.