Ch. 1 The Nature of Science

1.1 The Methods of Science

What is science?

• Science is a method for studying the natural world.
• Science comes from the Latin word Scientia, which means knowledge.
• Science is a process and investigation to gain knowledge about events in nature.

Major Categories of Science

• Life Science: Living Things
• Earth Science: Investigating Earth and Space
• Physical Science: Matter and Energy

Science Explains Nature

Scientists originally believed that heat was a fluid with no mass, due to it moving away from a warm body in all directions.

• Although, after further investigation, the scientists changed their explanation of what heat is.

Investigations

Ways investigations can take place:

• Observing something that occurs, and recording the observations
• Setting up experiments to test the effect of one thing on another
• Building a model that resembles things in the natural world and testing it to see how it reacts

Scientific Methods

Scientific Method - an organized set of investigation procedures.

Most investigations follow a general pattern of six steps:

1. Stating a problem
2. Gathering information
3. Forming a hypothesis
4. Testing the hypothesis
5. Analyzing the data
6. Drawing conclusions

If the results conclude that your original hypothesis is supported, you will move on to retesting your hypothesis several times.

• Although if your original hypothesis isn’t supported then you will modify your hypothesis and test the new one.

Stating a Problem

Many scientific investigations begin with someone observing an event in nature and wondering why or how it works

• then that question (why or how) becomes the problem.

Researching and Gathering Information

Before testing a hypothesis, learn as much as possible about the background of the problem

• Find out if others have found information that may help determine what tests to try.

Forming a Hypothesis

Hypothesis - a possible explanation for a problem using what you know and what you observe.

Testing a Hypothesis

Some hypotheses can be tested by making observations while others may be tested by building a model and testing it on real-life situations

• an experiment is a common way to test a hypothesis.

Experiment - test the effect of one thing on another using controlled conditions.

Variables

Most experiments contain at least two variables

Variable - a quantity that can have more than a single value.

Dependent Variable - one that’s value changes according to the changes in the other variables.

Independent Variable - is one that you change to see how it will affect the dependent variable.

Constants and Controls

Constant - a factor that does not change when other variables change.

Control - the standard by which the test results can be compared.

Analyzing the Data

An important part of every experiment includes

• recording observations
• organizing the test data into easy-to-read tables and graphs.

Another important part is interpreting the data and analyzing the observations

• if the data is not organized in a logical manner, wrong conclusions can be drawn.

Drawing Conclusions

Based on the analysis of your data, you decide whether or not your hypothesis is supported.

For your hypothesis to be considered valid and wildly accepted, the experiment must result in the exact same data every time it is repeated.

• Although, if your experiment does not support your hypothesis, you must reconsider the hypothesis.

Being Objective

Scientists need to be careful to reduce bias in their experiments

Bias - occurs when what the scientists expect changes how the results are viewed.

• Scientists can lessen bias by running as many trials as possible and by keeping accurate notes of each observation made.

Visualizing with Models

Sometimes, scientists cannot see everything they are testing due to observing something that is too large, too small, or takes too much time to see completely.

Model - represents an idea, event, or object to help people better understand it.

Models in History

One scientist named Lord Kelvin was famous for making models.

Kelvin’s work is still used to explain the nature of temperature and heat still is used today.

High-Tech Models

What can you use to create a scientific model?

• Computers
• Simulators

Scientific Theories and Laws

Scientific Theory - an explanation of things or events based on knowledge gained from many observations and investigations.

• If scientists repeatedly repeat an investigation that results in the hypothesis being supported, it is then considered a theory.

Scientific Law - a statement about what happens in nature that seems to be true all the time.

• Laws will tell you what will happen under certain circumstances but they don’t explain why or how something happens.

A theory can be used to explain a law.

The Limitations of Science

Science can help you explain many things in this world, but it cannot explain or solve everything.

Using Science—Technology

Technology - is the application of science to help people.

• Technology doesn’t always follow science
• Science and technology do not always produce positive results.

1.1 Summary

What is Science?

• Scientists ask questions and perform investigations to learn more about the natural world

Scientific Methods

• Scientists perform the six-step scientific method to test their hypotheses.

Visualizing with Models

• Models help scientists visualize concepts

Scientific Theories and Laws

• A theory is a possible explanation for observations while a scientific law describes a pattern but does not explain why things are happening.

Using—Technology

• Technology is the application of science to our everyday lives

1.2 Standards of Measurement

Units and Standards

A standard is an exact quantity that people agree to use to compare measurements

Measurement Systems

Parts of the English Metric System

• Feet
• Gallons
• Pounds

Most other nations use the metric system

The metric system is a system of measurement based on multiples of ten

International System of Units

In 1960, they improved the metric system and it is known as the International System of Units

SI - International System of Units

All types of SI measurements have a base unit:

(Quantity Measured, Unit, Symbol)

• Length: meter: m
• Mass: kilogram: kg
• Time: second: s
• Electric current: ampere: A
• Temperature: kelvin: K
• Amount of substance: mole: mol
• Intensity of light: candela: cd

SI Prefixes

Prefixes are used to indicate what multiple of ten should be used with that unit

Common SI Prefixes:

(Prefix, Symbol, Multiplying Factor)

• Kilo-: k: 1,000
• Deci-: d: 0.1
• Centi-: c: 0.01
• Milli-: m: 0.001
• Micro-: μ: 0.000001
• Nano-: n: 0.000000001

Converting Between SI Units

A conversion factor is a ratio that is equal to 1 and is used to change one unit to another

Measuring Distance

In scientific measurement, length is the distance between two points

Metric rulers and metersticks are used to measure length

Choosing a Unit of Length

The size of unit you measure will depend on the size of the unit being measured

Measuring Volume

Volume - the amount of space occupied by an object

Volume is expressed in being cubic.

• For example, cubic meters: m3

Measuring Liquid Volume

Most common units for expressing liquid volumes are liters and milliliters

A liter occupies the same volume as a cubic decimeter, dm3

Measuring Matter

Mass - measurement of the quantity of matter in an object

Density

The mass and volume of an object can be used to find the density of the material the object is made for

Density is the mass per unit volume of material

You find density by dividing an object’s mass by the object’s volume

Derived Units

A unit obtained by combining different SI units is called a derived unit

An SI unit multiplied by itself is also a derived unit

Measuring Time and Temperature

Time is the interval between two events

The SI unit for time is the second (s)

What’s Hot and What’s Not

Temperature will be explained further in-depth in a later chapter so for now think of it as a measure of how hot or cold something is

For most scientific work, temperature is measured on the Celsius (C) scale

• Freezing point of water: 0°C
• Boiling point of water: 100°C

Kelvin and Fahrenheit

Zero on the Kelvin scale (0 K) is the coldest temperature also known as absolute zero

• Absolute zero is equal to -273°C
• Degree symbols (°) are not used on the Kelvin scale

The Fahrenheit scale was roughly based off of the temperature of the human body (98.6° F)

1.2 Summary

Units and Standards

• When making measurements, it is important to be accurate

Measurement Systems

• The International System of Units, or SI, was established to provide a standard of measurement and reduce confusion
• Conversion factors are used to change one unit to another and involve using a ratio equal to 1

Measuring

• The size of an object being measured determines which unit you will measure in

1.3 Communicating with Graphs

A Visual Display

Graph - visual display of information or data

Graphs are useful for displaying numerical information in business, science, sports, advertising, etc.

Different kinds of graphs include:

• Line
• Bar
• Circle

Graphs make it easier to understand complex patterns by displaying data in a visual manner

Line Graphs

A line graph can show any relationship where the dependent variable changes due to a change in the independent variable

Line graphs often show how a relationship between variables changes over time

Multiple events can be shown on the same line graph

Constructing Line Graphs

Choose a scale that makes a graph readable

Always use the x-axis for the independent variable

Always use the y-axis for the dependent variable

Units of measurement are another factor in constructing line graphs

Line graphs can be made by calculators or by hand

Bar Graphs

A bar graph is useful for comparing information collected by counting

Uses for bar graphs include comparisons, or as data in promotional materials

Each bar represents a quantity counted at a particular time

Circle Graphs

A circle graph (pie graph) is used to show how some fixed quantity is broken down into parts

The circular pie represents the total

The slices represent parts and are usually represented as percentages of the total

When using any graph, think carefully about the conclusions you can draw from them and make sure they are based on accurate information

1.3 Summary

A Visual Display

• Graphs are a visual representation of data
• Scientists often graph their data to detect patterns
• The type of graph used is based on the conclusions you want to identify

Line Graphs

• A line graph shows how a relationship between two variables changes over time

Bar Graphs

• Bar graphs are best used to compare information collected by counting

Circle Graphs

• A circle graph shows how a fixed quantity is broken down into parts

Ch.1 Study Guide (Reviewing Main Ideas)

1.1 The Methods of Science

1. Science is a way of learning about the natural world
2. Scientific investigations can involve making observations, testing models, or conducting experiments
3. Scientific experiments investigate the effect of one variable on another. All other variables are kept constant
4. Scientific laws are repeated patterns in nature. Theories attempt to explain how and why these patterns develop

1.2 Standards of Measurement

1. A standard of measurement is an exact quantity that people agree to use as a basis of comparison. The International System of Units (SI) was established to provide a standard and reduce confusion
2. When a standard of measurement is established, all measurements are compared to the same exact quantity—the standard. Therefore, all measurements can be compared with one another
3. The most commonly used SI units include: length—meter, volume—liter, mass—kilogram, and time—second
4. In SI prefixes are used to make the base units larger or smaller by multiples of ten
5. Any SI unit can be converted to any other related SI unit by multiplying the appropriate conversion factor

1.3 Communicating With Graphs

1. Graphs are a visual representation of data that make it easier for scientists to detect patterns
2. Line graphs show continuous changes among related variables. Bar graphs are used to show data collected by counting. Circle graphs show how a fixed quantity can be broken into parts
3. To create a circle graph, you have to determine the angles for your data
4. In a line graph, the independent variable is always plotted on the horizontal x-axis. The dependent variable is always plotted on the vertical y-axis