INFORMATION Syllabus Safety DO/COLLECT: Pre-lab #2 MICROWORLDS – Four entries due by end of 3 rd lab (week 3)

Lab 2: Processes and Tools of Scientific Inquiry

Two Approaches to Science DISCOVERY SCIENCE No experiments Based on observations Inductive reasoning – general principles derived from large number of specific observations 3 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 Design VARIABLES: 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 GroupExperimental Group 7 WATER WATER + FERTILIZER

Only once? How many times should you do an experiment? How should you test multiple samples? 8

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 9

Lab: Black Box Experiment Identify what is contained in your box without peeking!

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

Tools for Scientific Inquiry: Scientific Notation 1 x  positive number = multiply by x m  negative number = divide by

Tools for Scientific Inquiry: Scientific Notation MULTIPLICATION: Add the exponents EX: (2 x 10 4 )(3 x 10 5 ) = 6 x * = DIVISION: Subtract the exponents EX: (6 x 10 9 ) / (3 x 10 5 ) = 2 x / = 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 It’s all about powers of TEN

Metric PrefixMeaning kilo (kilometer, kilogram)1000 meter, liter, gram1 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)

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. 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 = cm 200 m * 1 x 10 2 cm = cm = 2 x 10 4 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

Lab: Appendix A - Measuring Read the information in the lab Practice measuring with a pipette, graduated cylinder, balance, ruler/meter stick Be able to answer the questions in the Study Guide in preparation for the quiz next week!