WELCOME TO THE LAB!!

INFORMATION

• Go over Syllabus (brief)

• Go over MICROWORLDS (brief)– Two entries due by end of 2nd lab (week 2).– Two entries due by end of 4th lab (week 4).– These 4 & 6 additional by the end of lab 10.– Samples that may be done today include pond

water and algae. Do not use oil today.– Will have some time at the end of most labs.

LAB SAFETY - it’s mostly common sense:• THINK ABOUT WHAT YOU ARE DOING BEFORE YOU

DO IT!!• THINK ABOUT THE CONSEQUENCES!!• LISTEN TO SPECIAL INSTRUCTIONS!!• Go over safety/disposal stuff.

Prelabs (found on my web site):• DO/COLLECT: Pre-lab #1.• Normally done as homework & turned in at the start

of the lab. Prelab2 due at the start of the next lab.

Lab 1: The Metric System and the Scientific Method

Two Approaches to Science

DISCOVERY SCIENCE• No experiments• Based on observations• Inductive reasoning –

general principles derived from large number of specific observations

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EXAMPLE: All living things are composed of cells

Two Approaches to Science

HYPOTHESIS-BASED SCIENCE• Involves carefully planned experiments• Based on observations• Deductive reasoning – takes a general

statement and extrapolates specific results we would expect

Experimental DesignVARIABLES: things that

might change during the experiment

• INDEPENDENT VARIABLE: what you are changing in the experiment (what you’re testing)

• DEPENDENT VARIABLE: what you are measuring

• CONSTANT VARIABLES: things that are the same between your groups

The DEPENDENT VARIABLE depends

on the INDEPENDENT VARIABLE

The DEPENDENT VARIABLE depends

on the INDEPENDENT VARIABLE

Experimental Design – Controlled Experiments

You generally have two groups:1. CONTROL GROUP (CONTROL TREATMENT):

The group you are going to compare to; the one you don’t do anything to

2. EXPERIMENTAL GROUP: The group(s) on which you are testing something

Controlled Experiment

Control Group Experimental Group

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WATER

WATER +

FERTILIZER

Only once?

• How many times should you do an experiment?

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Sampling Error

• Draw 1 jelly bean?• Draw 10 beans?• Draw 100 beans?• Draw all the beans?

• SAMPLE SIZE: The number of samples, the more the better

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Scientific Notation and the Metric System – Appendix A

• SCIENTIFIC NOTATION: More compact form of a very large or very small number

• The distance to the Sun's nearest neighbor Alpha Centauri is greater than 10,000,000,000,000,000 m.

Tools for Scientific Inquiry: Scientific Notation

• Tells you how many times you must multiply or divide by 10 to get the number

• A number x 10B

• The distance to the Sun's nearest neighbor Alpha Centauri is greater than 1 x 1016m.

Tools for Scientific Inquiry: Scientific Notation

• 1 x 1016 positive number = multiply by 1010000000000000000• 1 x 10-16m negative number = divide by 100.0000000000000001

Tools for Scientific Inquiry: Scientific Notation

• MULTIPLICATION: Add the exponentsEX: (2 x 104)(3 x 105) = 6 x 109

20000*300000 = 6000000000• DIVISION: Subtract the exponentsEX: (6 x 109) / (3 x 105) = 2 x 104

6000000000 / 300000 = 20000

Tools for Scientific Inquiry: The Metric System

Metric System• Science uses the metric system. • The metric units are:

– meter for distance (measurement from one point to another)

– liter for volume (ie, the space that 1 liter of water occupies)

– gram for mass (weight), – and degree Celsius for temperature.

• metric units do not advance like English: grain, ounce, pound, ton

• they advance using prefixes & powers of ten

Metric how to use• Not covered well in the manual, it is all

about powers of TEN

Metric Prefix Meaning

kilo (kilometer, kilogram) 1000

meter, liter, gram 1

centi (centimeter, centiliter, centigram)

1x10-2 (1/100 or 0.01)

milli (milliliter) 1x10-3

micro (micrometer)1X10-6 (distance in microscopes)

nano (nanometer)1X10-9 (distance in electron microscopes)

other prefixes are not commonly used giga is used only in gigabytes & in Back To The Future (1.21 jig-ă-wăts)

• Another way to use metrics is to simply move the decimal to the left when going up the steps and move the decimal to the right when going down the steps.

• For example, when converting from 9.9 kilograms to grams we are going down 3 steps, so move the decimal three places right or 9.9000 kg = 9900.0 grams

Metric units are convertible. • 1 cubic centimeter (or 1 cc) of water is equal to

1 milliliter (ml) which is equal to 1 gram of water at sea level (& 1 BTU rises 1 cc 1°C).

• This does not work if water is not the material of study!

Metric System

Basic Metric Measurements• You will measure water in a

cylinder, tends to stick to the sides, especially with glass.

• This makes the meniscus, the boundary between the air and the water, curved.

• The correct way to read it is to read it from the bottom of the meniscus!

Converting Units

• Set up equations to cancel out units

200 m = cm200 m * 1 x 102 cm = 20000 cm = 2 x 104 cm

1 m

•THINK ABOUT YOUR ANSWER: Should there be more cm than m? Should there be fewer?•DOES YOUR ANSWER MAKE SENSE??

•THINK ABOUT YOUR ANSWER: Should there be more cm than m? Should there be fewer?•DOES YOUR ANSWER MAKE SENSE??

Practice Question

250 cm =• Meters?

• Millimeters?

Measurements

Accurate• How close is the

measurement to the true value?

Precise• How consistently can a

measurement be reproduced?

Measurements• Use a measuring tool that is close to the measurement you

want to make

For example, you would want to measure an ice cream bar in grams and an elephant in kilograms and not vc. vs.

Lab:

• Read the information in the lab• Practice measuring with a pipette, graduated

cylinder, balance, ruler/meter stick• Be able to answer the questions at the end of

the lab in preparation for the quiz next week!

Lab: Black Box Experiment

• Identify what is contained in your box without peeking!

• Use what is available to you in the lab and the scientific method!

• Fill in the Black Box Experiment Data Sheet in the lab and write your estimate

• Check it with me (if incorrect, try making a 2nd and 3rd experiment)

• When done, you may work on Microworlds (w/o using oil!)

What you’re responsible for

• I AM giving a quiz on the lab next week• Questions for the quiz will be pulled from the

lab and the study guide. Most labs have questions at the end, I suggest you DO THEM!

• Lab1 and prelab2 will be turned in at the start of lab2. Other than laba 1 & 10, the labs will not normally be turned in.