the nature of science objective 1 - biology...
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The Nature of Science
Goals of Science
Investigate and understand nature
Explain events in nature
Make useful predictions
Never stop questioning
Definition of Science
An organized way of using evidence to learn about the natural world.
The body of knowledge that scientists have built up after years of testing proposed explanations.
Science vs. Technology
Science is the knowledge gained from experimentation.
Newton’s Laws
Theory of Relativity
Ohm’s Law
Human Genome Project
Technology is the use of science knowledge to make things.
Calculators & computers
Atomic Energy
Electric motors
Gene therapy
Antibiotics
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Observations
The first step to “doing” science
Involves using one or more of the senses
– Sight
– Hearing
– Touch
– Smell
– Taste
These observations led to more questions . . .
Which led to proposed answers,
now called hypotheses.
Observations
Will raise a question.
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Observations
To gather…
Information
Evidence
Data
Inference
Follows an observation
A logical interpretation based on prior knowledge and experience
Uses what you know to figure something out
Inference
Observation or Inference?
There are two dogs.The little dog stole the big dog’s bed.The big dog is in the little bed.The little dog is mad.The big dog is sleeping.The little dog is in a big bed.There are two dog beds.There is a chair by the dog beds.The dogs are not allowed in the chair.The dogs are friends.The big dog is happy.The little dog is gray.The little dog is old.
Observation or Inference?
Can we make
the same assumptions
(Inferences
based on observations)
about this picture as we
did the last
one?
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Observations and Inferences
How do scientists find answers
to questions?
The Scientific Method
Formal experimentation
follows the steps of the scientific method.
Many discoveries in science were not made
using the scientific method, but this method
was used to confirm
those discoveries.
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Scientific Method
It is a method of research in which a problem is identified,
relevant data are gathered, a hypothesis is formulated from these data, and the hypothesis is empirically tested.
Hypothesis
A tentative statement that proposes a possible explanation to some phenomenon or event
Attempts to explain a set of observations
May arise from logical inferences
Experimental Design
Define the problem.
Make a testable hypothesis.
Define the variables, independent, dependent and controlled.
Determine appropriate sample size.
Run the experiment.
Variables – MIX
Manipulated or Independent
Variable is the one you are changing and is first in a data table and
plotted on the X-axis of the graph.
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Variables - DRY
Dependent or Responding variable is second column in a data table, and plotted on the Y-axis of a graph.
A Control vs. Controlled Variables
Control or control group is one that participates in the experiment without the change being tested. (Receives a placebo, or grown under the same conditions.)
Controlled Variables are the other factors in an experiment that might affect the results. (Amount of water, sunlight, strength of the drug, food.)
Data Collection and Sample Size
The larger the amount of data collected,
The larger the sample size,
The more times the experiment is repeated,
The more valid are the results.
Validity
Does the experiment measure what it claims to measure?
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Analysis of the Data
Data tables, flow charts and graphs present the information collected during an experiment.
What the data shows, any trend in information is explained in the analysis of data.
Data Presentation and Analysis
Data tables are lists of information that may or may not show a relationship.
Graphs are pictorial representations of information to aid in seeing any relation between them.
Data Tables
The first column is usually the independent variable, or what was being changed.
Other columns are counts or measurements that
were taken at each change.
The table shows environmental factors and soybean production for three regions.
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Reading Graphs Always read the
title.
Read the x- & y-axis labels & UNITS.
What is happening?
As the pressure of oxygen increases, the % saturation is
increased.
Graph Types – Pie and Bar
Pie Graphs are used to show
parts of a whole and percent
distributions.
Bar Graphs show
noncontinuous data such as
number of males and
females in each science
class with different hair
colors.
Graphs – Line or Curves
Line Graphsshow continuous data like distance vs. time, acceleration, or change over time.
Data Trends
Directrelationship means as one variable changes, the other changes in the same way.
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Other Data Trends
Inverse – when one goes up the other one goes down or as one goes down the other goes up.
Exponential – typical of uncontrolled growth of a population, is a J-shaped curve
Drawing conclusions
Not getting the results expected, or predicted often provides more information than getting what you expected.
Ernest Rutherford did not expect his light to go straight through the gold foil, but it showed him that atoms were mostly empty space. A very important discovery.
What if the data doesn’t support the hypothesis?
Some very important discoveries occurred when the
scientist was actually looking for something else. For example, the discovery of some antibiotics.
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Validating Scientific Claims
Weigh the evidence!!!
Be careful what you conclude!!!
There are a lot of false claims out there!!!
When analyzing data . . . Compare the data trend to
the hypothesis.
Does the data agree?
Does it show the opposite?
Could there be another reason that the trend agrees with the hypothesis? Did all other factors get controlled?
Scientific Theory
Based upon experimental data.
A broad principle of nature that has been supported over time.
Confirmed by repeated experiments.
May be modified as new information is gathered.
Scientific Law
Conclusions about relationships in nature that presently have no exceptions.
Scientists work to understand why these relationships exist.
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Tools for Measurement
Clocks and stopwatches measure time.
A balance is used to measure mass.
A graduated cylinder, dropper, or
volumetric flask is used to measure liquid
volume.
A metric ruler is used to find length, and
therefore the volume of regular objects.
Measuring Units – System Internationale
Mass?
Volume?
Length?
Grams
Liters
Meters
Accuracy
This is when a measurement is closest to its true value (the bull’s eye!).
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Precision
This is the repeatability of a measurement.
It may or may not be accurate
It is possible to be accurate and precise!
Is it accurate? Is it precise?
Accuracy depends on how close the measurement tool is to the actual measurement.
If the equipment has been properly calibrated and cared for it is usually accurate.
Precision usually depends on the amount of estimating that has to be done.
The smaller the measurement markings on the tool, the more precise it is.
Experimentation and Safety Use only labeled
materials.
Read labels twice to make sure.
Know the procedure.
Ask about the MSDS (material safety data sheets) if you are not familiar with the substance.
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Safety In the Science Lab
Rules and Symbols
Lab Safety: Everyone Is Responsible! Safety First
Science is a hands-on laboratory class.
You will be doing many laboratory activities, which require the use of hazardous chemicals and expensive lab equipment.
Safety in the science classroom is the #1 priority.
To ensure a safe science classroom, a list of rules has been developed and provided to you in your student safety contract.
These rules must be followed at all times.
A signed lab safety contract is required to participate in labs.
General Safety Guidelines
Be Responsible at All Times. No horseplay, practical jokes, pranks, etc.
• Follow all instructions carefully.
• Do not use the lab equipment until instructed to do so.
• Food, drink, and gum are not allowed in the science classroom.
Lab Safety: Everyone Is Responsible!
General Safety Guidelines
Keep the science room clean and organized.
Lab Safety: Everyone Is Responsible!
• Notify the teacher immediately of any accidents or unsafe conditions in the science classroom!
• Wash your hands with soap and water after experiments.
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• Wear safety goggles when working with chemicals,
flames, or heating devices.
• If a chemical gets in your eye, flush in water for 15
minutes and notify the teacher.
Safety PrecautionsEye Protection
Sharp Objects• When using knifes or other sharp objects always
walk with the points facing down.
• Cut away from fingers and body.
Electrical Safety• Do not place a cord where someone can trip over it.
• Never use electricity around water.
• Unplug all equipment before leaving the room.
Safety PrecautionsHeating Safety
• Tie back hair and loose clothes when working
with open flames.
• Never look into a container as you are heating it.
• Heated metal and glass looks cool, use tongs or
gloves before handling.
• Never leave a heat source unattended.
Safety PrecautionsChemical Safety
• Read all labels twice before removing a chemical from
the container.
• Never touch, taste, or smell a chemical unless instructed
by the teacher.
• Transfer chemicals carefully!
Hand Safety
• If a chemical spills on your skin, notify the teacher and
rinse with water for 15 minutes.
• Carry glassware carefully.
Plant Safety• Do not eat any plants in lab.
• Wash your hands after handling plants.
Lab Safety
• Food
• Drink
• Smoking
• Cell phone
• Horseplay
• Open-toed shoes
Prohibited
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Lab Attire
• Gloves (as needed)
• Goggles (as needed)
• No open-toed shoes
• No shorts
• No spaghetti straps or sleeveless
shirts (including muscle shirts
• The less skin revealed The safer
you are.
Lab Attire
Behavior
• Have a positive attitude!
• Work cooperatively with
group members.
Safety Equipment
Fire Blanket – Located in back of classroom in the white container
• Fire Extinguisher – Located in back of
classroom in the white container
To operate the fire extinguisher remember P-A-S-S
P- Pull the Pin
A-Aim the hose at the base of the fire from 5-6 feet away.
S-Squeeze the handle.
S-Sweep the hose back and forth across the fire.
REMEMBER: Stop, Drop, & RollOn Fire?
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What’s Wrong With This Picture?
What’s Wrong With This Picture?
What’s Wrong With This Picture?
What To Do In An Emergency
If there is a fire or fire alarm• Quietly get up and push in your chair.
• Walk toward the outside classroom door.
• Walk to the basketball court.
• Quickly line up in alphabetical order by last name.
• Remain in line until the drill is over.
• Remain silent throughout the entire alarm so that all
people can hear important directions.
Lab Safety: Everyone Is Responsible!
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Any Questions?
REMEMBER:
• Carefully read through the entire safety contract
and sign.
• Have your parents read and sign your safety
contract.
• Study for the safety quiz later this week!
Safety with Temperature Changes
Do not handle hot or cold containers.
Use the proper holder for the container.
When heating a substance, aim it away from everyone.
Safety with Gases
Odors are tested by wafting.
Reactions which produce gases should be done in a fume hood.
Gases should be trapped only in a large volume container to provide for rapid expansion.
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Safety Equipment
Protective goggles are worn in lab at all times.
Non-ventilated are worn if contact lenses are worn.
Aprons should be worn when handling chemicals.
Follow MSDS for safe handling of all chemicals.
OK, we are done!!!