Scientific Method Scientific Method

Steps of the Scientific Method  Observation  Hypothesis  Prediction  Testing  Please write down an example of each as we discuss  Homework page

 Go over homework…..page  Parent letters?

Hypothesis  This is an educated guess based upon observation  The Gaia Hypothesis

Theory  A theory is an explanation of a set of related observations or events based upon proven hypotheses and verified many many times by objective groups of researchers. One scientist cannot create a theory; he can only create a hypothesis.  A theory is like a car. Components of it can be changed or improved upon, without changing the overall truth of the theory as a whole.

Theory  An automobile has many moving parts, all designed to move you. An automobile is very complex. Sometimes, improvements are made to one or more component parts. A new set of spark plugs that are composed of a better alloy that can withstand heat better, for example, might replace the existing set. But the car still performs the same way.

LAW  Scientific Law---This is a statement of fact –very brief-meant to explain an action or set of actions. It is generally accepted to be true and universal. It is a simple explanation for a natural occurrence.  A law is more like a slingshot---A slingshot has but one moving part--the rubber band. If you put a rock in it and draw it back, the rock will fly out at a predictable speed, depending upon the distance the band is drawn back.  Usually summarized with an equation

Graphing  Identify the variables Independent Variable - (controlled by the experimenter) Goes on the X axis (horizontal) Should be on the left side of a data table. Dependent Variable - (changes with the independent variable) Goes on the Y axis (vertical) Should be on the right side of a data table

Determine the variable range Determine the variable range  Subtract the lowest data value from the highest data value.  Do each variable separately.

Determine the scale of the graph. Determine the scale of the graph.  Determine a scale, (the numerical value for each square), that best fits the range of each variable.  Spread the graph to use MOST of the available space.

Number and label each axis.  This tells what data the lines on your graph represent  What is wrong with the following graph

Plot the data points Plot the data points  Plot each data value on the graph with a dot.  You can put the data number by the dot, if it does not clutter your graph

Title the graph.  Your title should clearly tell what the graph is about.  If your graph has more than one set of data, provide a "key" to identify the different lines.

Other types of Graphs  Bar graph –many types---things that are counted Bar graphmany typesthings that are counted Bar graphmany typesthings that are counted  Circle graph—shows how a fixed quantity is broken down into parts Circle graphshows Circle graphshows  Histograms and bar graphs look very similar—but a histogram is defined as a bar graph that shows frequency data. Histograms

 Parent letters  Lab reports are due tomorrow by each person and they count as a project grade

SI system  K H D (unit) d c m  I e e meter e e I  L c c liter c n L  O t a gram i t L  o I I

1.You will decide what unit you are changing FROM and what unit you are changing TO. 2. Starting at the FROM unit, count over (keeping in mind "left" or "right") to the TO unit. **This will be the number of places you will move the decimal in your answer.

 EXAMPLES: 32 kilograms = ______________ grams You want to change FROM kilograms TO grams. Use diagram and count over, starting at kilograms to grams.  K H D (grams) D C M  S tart 1-> 2-> 3  S tart 1-> 2-> 3

If you are converting from a 'bigger' unit to a 'smaller' unit, move the decimal point to the right.

If you are converting from a 'smaller' unit to a 'bigger' unit, move the decimal point to the left.

 'dec-' means as in decimal, decade; so a decimeter is one-tenth of a meter. Move one decimal place.  'cent-' means as in percent, century; so a centimeter is one-one hundredth of a meter. Move two decimal places.  'milli-' means 1, as in millipede. Oh, well. A millimeter is one-one thousandth of a meter. Move three decimal places.

 1 meter is how many millimeters?  1 meter is how many millimeters?  [1 m = ___________ mm] Meter is bigger than millimeter, so you move the decimal point to the right. Millimeter differs from meters by three decimal places. Move the decimal three places to the right. 1 m = 1000 mm.

 3.2 m is how many centimeters?  3.2 m is how many centimeters?  [3.2 m = _________ cm] Meter is bigger than centimeter, so you move the decimal point to the right. Centimeter differs from meter by two decimal places. Move the decimal two places to the right. 3.2 m = 320 cm.

Complete these examples  0.5 m is how many mm?  m is how many cm?  4.5 cm is how many mm?  45 mm are how many m?

1--Meters to millimeters is three places to the right..5 m = 500 mm. 2--M to cm is two places to the right m = 4.5 cm. 3--Cm is bigger than mm. Cm and mm differ by one decimal point. Move the decimal point once to the right. 4.5 cm = 45 mm. 4--Mm is smaller than m, so the decimal point moves to the left. Mm differ from m by three decimal places. Move the decimal point to the left three places. 45 mm = m.

Standards  There must always be an exact quantity that people use to agree to use for comparison  Just like every experiment must have a control  meter (m)distance"The metre is the length of the path travelled by light in vacuum during a time interval of 1/ of a second.“ meter  second (s)time"The second is the duration of periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.“ second  ampere (A)electric current"The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross- section, and placed 1 metre apart in vacuum, would produce between these conductors a force equal to 2 × ampere

Base units  The most frequently used base units  See page 15  Prefixes and base units  You must memorize this

 Complete concept map  Take up lab  Book covers due TUESDAY  Test is Friday changed  Complete mini lab for homework/test review  Complete skills activity page 16 or worksheet

 Page 16 answer  1cm=10mm  11cm X 10mm 1cm 1cm  Cm cancel out and complete the math  11 x 10mm=110mm

Volume Liquid volume—there is no side to measure so………….you want to know how much will a container hold Most common units are liter and milliliter Formula = l x w x h Units are always cubed cm3 dm3 L3 1ml=1cm3

Density  Density = Mass/Volume Mass   how could you distinguish a metric ton of feathers versus a metric ton of bricks if you could not see them?

 One metric ton of either feathers or bricks will have same mass of1,000 kilograms (one metric ton).  a metric ton of feathers will occupy a volume of almost 400 million cm3(about the size of four tractor trailer trucks),  a metric ton of bricks will occupy only one- half million cm3 (about the size of a large- screen TV).

 The bricks are denser than the feathers because their mass is packed into a smaller volume. This relationship between the mass and volume of a substance is what defines the physical property of density

Derived units Derived units  Don’t ever forget to put the unit when you are discussing any measurement  combinations of the base units.