Scientific Method and Measurement Notes

Key: Write down RED words in your notes.

Bell Ringer: Name 2 disciplines (ex: Biology) in

science and what their focus is

Explain in your own words what Science is.

What is science? The search for truth. Discovering how the world works.

An attempt to understand the world we live in.

Scientific Method In order to get accurate results, a

reliable process must be used.

A way to solve problems

Basic Steps:1. Define the problem/ ask questions2. Hypothesis3. Experiment4. Observe and gather data5. Analyze data6. Conclusion7. Peer review

Observations You must observe things to create

questions about them.

Observation vs. Assumption– Observation = what you see– Assumption = a judgment or opinion

Hypothesis A hypothesis is an educated prediction

of what you think will happen in the experiment.

A hypothesis must be falsifiable. If it can not potentially be proven false, then there is nothing to test.

Example…

Why is the following example not falsifiable, therefore not testable??

Example…

``the moon is populated by little green men who can read our minds and will hide whenever anyone on Earth looks for them, and will flee into deep space whenever a spacecraft comes near''

Practice “Scott and Ian, identical twins, are sleepy

every day in their 1:00 history class: they often doze and want to know why, so they can prevent the drowsiness and improve their history grades.”

Make a list of possible hypotheses about why they are sleepy.

Reasons why the twins are sleepy:

1. They do not like history Class 2. They think the teacher is boring 3. They are in food comas after lunch

and are sleepy as a result 4. They do not get enough sleep at

night.

Experiment All experiments have two main groups:

– The Test Group– And the Control Group

– These two groups are exactly the same except for the one thing you are testing.

Test Group Contains the variable you are testing

– Example: Plant WITH fertilizer– Example: Patient WITH medication

– **Make sure you are only testing ONE thing at a time.

Control Group This group serves as a comparison

to the test group. This group has “normal” conditions.

– Example: Plant is given no fertilizer– Example: Patient is given a placebo/fake

medication.

Controls and Variables The test group should have only ONE

variable (what you are testing).

All other variables between your groups must be the same.

Independent Variable The variable you are testing.

– The amount of light a plant gets– How much exercise a rat gets– The class that the twins are sleepy in

Dependent Variable What you are measuring

– The results of the independent variable

– How much carbon dioxide is excreted– The height of a plant– The weight of a rat– The sleepiness of the twins

Practice For each hypothesis you made for the

“sleepy twins”, write down the independent variable. (what you are testing)

1. They do not like history Class ID = Class 2. They think the teacher is boring ID= ________ 3. They are in food comas after lunch and are sleepy as

a result ID = _________ 4. They do not get enough sleep at night. ID = ________

Find the mistake

Draw this picture in your notes

Find the mistake

Too many Variables

-Size of cup

-Temperature of water

Find the problems

Draw this picture in your notes

Find the problems

Variables- Types of Soil

- Amount of light

-Type of Plant

Correct Set up

Avoiding errors and bias 1. Use large groups

2. Repeat the experiment

3. Take careful measurements

4. Don’t let personal opinions interfere.

Placebos A placebo is “fake medicine”, usually

a sugar pill given to the control group.

The patient thinks they are getting real medicine but are only getting a sugar pill.

The “effects” of the placebo can be compared with the effects of the real medicine.

Data Collection and presentation

In order for your experiment to remain reliable, your data must be reliable.

Make accurate measurements.

Don’t ignore data you don’t like or agree with.

Organize data into tables and graphs

A graph can make pages of data make more sense.

Overall patterns can be seen better with a graph.

Conclusion This is where you ask…. Did my data

support my hypothesis?

If your data supports your hypothesis, you are on your way to a theory.

If your data does not support your hypothesis, you try a different experiment.

Conclusion must be based on data.

Limitations of an experiment:

*You must be careful not to draw conclusions that are not supported by your data. In an experiment on rats, for example, conclusions cannot be

automatically applied to other animals.

Peer Review Why peer review?

– People make mistakes– People lie

Experiment results are published and other scientists check their work for mistakes and can repeat the experiment to see if it really works.

Hypothesis: educated guess

Theory: Hypothesis tested true many times.

Law: Still testing true and can lead to accurate predictions.

All scientific explanations are subject to change or improve!

Elements of good science Hypothesis must be testable Experiment must have a control group Only test one thing at a time. All variables must be the same

between the two groups. Large groups reduce errors. Repeat the experiment.

Primary Sources: (more accurate) Research reports, eye-witness

Secondary Sources: Text books, newspaper

Small groups If you test the effects of a medication

on two people instead of 100 people, why is that a problem?

MeasurementsMeasurement Metric

Unit

English

Unit

Tools

Length Meter Feet Ruler

Mass Gram Pound Scale

Volume Liter Gallon Graduated cylinder, beaker

Temperature Celsius Fahrenheit Thermometer

SI units scaleKilo- 1000

Deka- 10

(Base) 0

Deci- .1

Centi- .01

Milli- .001

Micro- .0000001

Nano- .000000001

Others Mega- Giga- Tera-

Unit Conversion

K H D B D C M

24 meters = _______ cm

997 mm = ______ km

Lab Equipment