The Methods of Science What is science? 1. A method for studying the natural world 2. From Latin word scientia which means “knowledge” 3. Follows rules or natural patterns

Major Categories of Science 1. Earth and Space Science (geology, meteorology, astronomy, etc.) 2. Life Science (genetics, botany, ecology, zoology, etc.) 3. Physical Science (matter & energy) The sciences often overlap

Science Explains Nature Explanations are modified as we learn more about the natural world often through new technology

Pure Science vs. Technology Pure science – scientists who do experiments to learn more about the natural world. Technology – the application of science for practical uses; can be controversial (i.e., genetic engineering, stem cell research)

Scientific Theories and Laws Theory – must be able to explain observations clearly and consistently (based on knowledge gained from many observations); not a guess; experiments that illustrate the theory must be repeatable with the same result; must be able to predict results from the theory. Law- a statement about what happens in nature and seems to be true every time; predicts what will happen in a given set of conditions, but does not explain how or why A theory can explain a law.

Scientific Method- An organized set of investigation procedures which includes: Stating a Problem Researching & Gathering Information Forming a hypothesis (a testable prediction) Testing a hypothesis includes: making observations building or using a model performing an experiment Designing a controlled experiment with multiple trials Gathering Data Analyzing Data Drawing Conclusions Being Objective (eliminating bias)

Variable - a quantity that can have more than one value. a. Independent Variable b. Dependent Variable c. Constants d. Control

Variable - a quantity that can have more than one value. a. Independent Variable - “you change it” b. Dependent Variable – “it changed” c. Constants – all of the things that remain the same d. Control – a standard for comparison

Making Observations Qualitative observations – using the 5 senses Quantitative observations – making measurements

Discover how long a foot is: 1. Measure the distance across your classroom using your foot as a measuring device. 2. Record your measurement and name your measuring unit. 3. Repeat steps 1 and 2 for each group member.

Discover how long a foot is: 1. Measure the distance across your classroom using your foot as a measuring device. 2. Record your measurement and name your measuring unit. 3. Repeat steps 1 and 2 for each group member.

Units of Measurement A. Units and Standards 1. Standard - an exact quantity that people agree upon using for measurement 2. Cannot compare measurements without a standard 3. A measurement consists of a number and a unit.

Measurement Systems 1. English System – (feet, yards, inches, miles, pounds, etc.) 2. Metric system – based on multiples of 10; devised by a group of scientists in the late 1700s.

International System of Units (SI) SI Units are used for consistency a. improved version of metric system in 1960s b. universally used and accepted by scientists world-wide c. Each type of measurement has a prefix & base unit (meter, Liter, gram)

4. SI Prefixes Kilo – Hecto- Deka – Basic Unit deci- centi- milli- (k) (H) (D) (m, L, g, s) (d) (c) (m)

5. SI Standards of Measurement Quantity MeasuredUnitSymbol Lengthmeterm Masskilogramk Timeseconds TemperaturekelvinK Amount of substancemolemol Electric CurrentampereA Intensity of Lightcandelacd

RulerLengthWidth Data Measure the length and width of an index card using the least precise to the most precise measuring device.

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6. Significant Figures All of the numbers in a measurement known for certain plus an estimated digit. (See Handout)

1.All digits 1-9 are significant. Example: 129 has 3 significant digits 2. Zeros between significant digits are always significant. Example: 5007 has 4 significant digits 3. Trailing zeros in a number are significant only if the number contains a decimal point. Examples: has 4 significant digits 100. has 3 significant digit 100 has 1 significant digit

4. Zeros in the beginning of a number whose only function is to place the decimal point are not significant. Example: has 2 significant digits has 1 significant digit 5. Zeros following a decimal significant digit are significant. Example: has 3 significant digits has 5 significant digits

ATLANTIC-PACIFIC RULE If the decimal is ABSENT, start with the first non-zero number on the ATLANTIC side and count going LEFT. If the decimal is PRESENT, start with the first non-zero number on the PACIFIC side and count going RIGHT.

How to write a very large number, such as 46,350,000 = x 10 7 coefficient Move the decimal until you get to a number The number of times moved is equal to the exponent.

When the number is less than one, the exponent will be negative = 2.24 x 10 -4

Scientific Notation Practice cm = cg = m = kg = g =

Scientific Notation Answers cm = 4.25 x 10 2 cm cg = 3.6 x 10 4 cg m = 9.8 x m kg= 1.35 x kg g = x 10 3 g

When adding or subtracting numbers in scientific notation, the power of 10 must be the same. Example: 3.6 x x 10 2 = 3.6 x x 10 3 = 4.1 x 10 3 OR 36 x x 10 2 = 41.2 x 10 2 = 4.1 x 10 3

When multiplying numbers in scientific notation, multiply the coefficients, then ADD exponents. Examples: 1. (3 x 10 2 )(2 x 10 5 ) = 6 x (4 x 10 4 )(5 x 10 5 ) = 20. x 10 9 = 2 x 10 1 x 10 9 = 2 x 10 10

When dividing numbers in scientific notation, divide the coefficients, then SUBTRACT exponents. Examples 1) 4 x 10 3 = 2 x = 2 x x ) 4 x = 2 x = = 2 x x 10 -2

How many seconds are in one year?

8. Converting Between SI Units Dimensional Analysis is a method of problem-solving that focuses on the units used to describe matter.

9. Dimensional Analysis A conversion factor -a ratio of equivalent values Example, 1 dozen = 12 eggs could be written: 1 dozen or 12 eggs 12 eggs 1 dozen

Examples: 1) 30 eggs = ______ dozen 30 eggs x 1 dozen = 2.5 dozen 12 eggs

2) 1.5 dozen = ______ eggs 1.5 dozen x 12 eggs = 18 eggs 1 dozen

3) If you buy 13.3 gallons of gasoline at $ /gallon, how much do you pay? 13.3 gal x $2.899 = $ gal (if it had been $2.89/gallon, it would be $38.44)

Kilo – Hecto- Deka – Basic Unit deci- centi- milli- 4) L = ________ mL 1 L = 1000 mL L x 1000 mL = 1225 mL 1 L

5) 5400 mg = ______ g 1000 mg = 1 g 5400 mg x __1 g__ = 5.4 g 1000 mg Kilo – Hecto- Deka – Basic Unit deci- centi- milli-

Measuring Distance 1. Length is the distance between 2 points. 2. Choosing a Unit of Length a. unit chosen depends on the size of the object.

Measuring Volume 1. Volume – the amount of space occupied by an object 2. Volume formulas: Rectangular Solids: V = lwh Cylinder: V = π r 2 h Sphere: V = 4 π r 3 3

Measuring Liquid Volume a. Usually expressed in Liters (L) or milliliters (mL) b. 1 cc = 1 cm 3 = 1 mL

Converting from Liters to cm L x 1000 mL x 1 cm 3 = 1500 cm 3 1 L 1 mL

Measuring Matter 1. Mass – a measurement of the quantity of matter in an object. The kilogram is the basic unit of mass in SI.

Density - the mass per unit volume of a material. ( D = m/v) MaterialDensity (g/cm 3 ) MaterialDensity (g/cm 3 ) hydrogen aluminum2.7 oxygen iron7.9 water1.0gold19.3

Derived Units a. A unit obtained by combining different SI units b. Examples: 1) density: g/cm 3 2) volume: m 3

F. Measuring Time & Temperature 1. Time - the interval between 2 events - SI unit of time is the second (s)

Temperature- measure of the average kinetic energy of the particles of matter - SI unit of temp. is Kelvin (K) - Absolute Zero: 0 K is - 273°C ( 273° lower than freezing pt. of water) - Do not use degree symbol with K. - Laboratory thermometers use Celsius scale - Fahrenheit scale will not be used the science lab

Temperature Conversions K= °C (Notice Kelvin does not have °) °C = 5 (°F-32) 9 °F = 9 °C

3. Percent Error Calculation % Error = |Accepted Value – Experimental Value | x 100 | Accepted Value | Accepted Values for pure substances can be found in the Handbook of Chemistry and Physics. Experimental Values are determined from measurements taken during an experiment.

Communicating with Graphs Graph - A visual display of information or data

Line Graphs 1. Can show any relationship where the dependent variable changes to a change in the independent variable. 2. Often show changes over time. 3. Independent Variable is plotted on x-axis 4. Dependent variable is plotted on y-axis 5. Refer to the “Components of an Excellent Graph”

Bar Graphs Useful for comparing information collected by counting.

Circle Graphs Used to show how some fixed quantity is broken down into parts.

Making a Circle (Pie) Graph a. Use a protractor to make a circle graph. 1) Determine the percentage of each component. (Make sure all %s add up to 100) 2) Change percentage to a decimal. 3) Multiply decimal by 360° 4) Draw a circle. Draw a line across the diameter. 5) Use the protractor to measure each angle.