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PREPARE FOR LABORATORY WORK

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Title: PREPARE FOR LABORATORY WORK


1
PREPARE FOR LABORATORY WORK
  • Never perform unauthorized experiments.
  • Know how to use the safety shower, eye wash,
    fire blanket and first aid kit bucket of sand.
  • Do not work in the lab without your teacher in
    the room.

2
DRESS FOR LABORATORY WORK
  • Tie back long hair.
  • Do not wear loose sleeves as they tend to get in
    the way.
  • Do not wear open shoes on a lab day.
  • Wear lab aprons during all laboratory sessions.
  • Wear safety goggles during all laboratory
    sessions

3
BUNSEN BURNER SAFETY
  • A Bunsen burner flame is very hot. The center of
    the flame will be over 1000 degrees Celsius.
    Treat burner flames with respect.
  • Always use the main gas shut off valve on the
    desk to shut off a Bunsen burner.
  • The valve at the base of the burner is only used
    to control the flame.

4
BUNSEN BURNER SAFETY
  • If your hair or clothing catches on fire stop
    drop and roll.
  • If someone else's hair or clothing catches on
    fire, wrap them with a fire blanket to smother
    the fire. Do not let them run.

5
AVOID HAZARDS
  • Use caution when handling hot glassware.
  • When diluting acid, always add acid slowly to
    water. Never add water to acid.
  • Keep caps on reagent bottles. Never switch caps.

6
ANIMAL SAFETY
  • Do not cause pain, discomfort , or injury to an
    animal.
  • Wash hands after handling animals

7
SAFETY WITH CHEMICALS AND DISSECTING SPECIMENS
  • Do not touch or taste any chemical unless
    specifically instructed to do so.
  • Read chemical labels more than once before using
    the contents - it is easy to confuse chemicals.
  • When working with chemicals or dissections, keep
    your hands away from your face. The skin on your
    face is much more sensitive to irritation than
    your hands.

8
SAFETY WITH CHEMICALS AND DISSECTING SPECIMENS
  • To smell something, hold it away from your nose
    and wave your hand over it towards your nose.
    This is called wafting. You may pass out or
    inhale dangerous gases is you just stick your
    nose over the container and breathe in.
  • Flush any chemical spill on your skin with plenty
    of water. The rule of thumb is 15 minutes.

9
SAFETY WITH CHEMICALS AND DISSECTING SPECIMENS
  • When heating anything in a test tube, point the
    mouth of the test tube towards a wall, away from
    people.
  • Do not lay the glass stopper from a reagent
    bottle on the lab table. Hold the handle of the
    stopper between two fingers while you pour from
    the bottle.
  • When mixing acids and water, pour the acid into
    the water. Remember, AnW (root beer)
  • Wash your hands when you are finished with the
    lab.

10
SAFETY WITH GLASSWARE BROKEN GLASS
  • Never use chipped or broken glass. If you notice
    chipped or cracked glassware during a lab please
    report it to the instructor to be replaced.
  • Broken glass should never be handled with your
    hands. Use a dustpan and broom to sweep up broken
    glass. Small pieces can be wiped up using a wet
    paper towel.
  • Broken glass should be placed in the proper
    container - either a can for broken glass or a
    sharps container.

11
SAFETY WITH GLASSWARE BROKEN GLASS
  • Always have the instructor clean up a broken
    mercury thermometer. Mercury is a poisonous
    substance and should not be handled.
  • Broken glass that has contacted blood must be
    disposed of in a sharps container.
  • The plastic cylinder guard on a graduated
    cylinder is to protect the cylinder from breaking
    if it should tip over. The cylinder guard is not
    made to slide up and down for measuring.

12
SAFETY WITH GLASSWARE BROKEN GLASS
  • A graduated cylinder should be laid down when it
    is empty - if it is laying down it can't be
    tipped over.
  • Remove glass tubing and funnels from stoppers as
    soon as your lab is finished. If you do not they
    will become stuck in the stopper.

13
BLOODBOURNE PATHOGEN SAFETY
  • Wear latex gloves anytime you assist someone who
    is or has been bleeding or vomiting.
  • Clean the entire area (desktop, floor, etc.) with
    a disinfectant when you are finished caring for
    the person.
  • Remove your latex gloves by pulling them off
    inside out. Avoid contact with the outside of the
    gloves.

14
BLOODBOURNE PATHOGEN SAFETY
  • All paper towels, tissues, latex gloves and other
    materials used to clean up blood and other
    possible infectious materials should be disposed
    of in the proper biohazardous waste bag.
  • Standard Biohazardous waste bags are red with the
    biohazardous waste symbol on them. If one is not
    available, use a regular plastic garbage bag and
    attach a biohazardous waste sticker to the bag.
  • Wash your hands thoroughly with a disinfectant
    when you are finished.

15
CLEAN UP
  • Consult teacher for proper disposal of chemicals.
  • Wash hands thoroughly, following experiments.

16
IN CASE OF ACCIDENT
  • Report all accidents and spills immediately.
  • Place broken glass in designated containers.
  • Wash all chemicals from your skin immediately
    with plenty of running water.
  • If chemicals get in your eyes, wash them for at
    least 15 minutes in an eyewash.

17
  • Were you to cut your finger while working in the
    lab you should ______.
  • not worry about it if it is not bleeding too much
  • wrap a wet paper towel around the cut and
    continue working
  • seek medical aid from a qualified person
  • go the first-aid kit yourself and place
    antiseptic on it

Answer C
18
  • Safety items such as goggles, tongs, heat
    insulated mittens, aprons, and rubber gloves
    should be used at ALL times while in the
    laboratory.
  • True
  • False

Answer B
19
  • Which is the correct way to hold a test tube
    while heating its contents? A. Pointing
    straight up. B. Pointing horizontally. C.
    Pointing away from yourself and others. D.
    Pointing straight at yourself.

Answer C
20
  • Why is it important to NOT run if your hair or
    clothing catches fire in a science lab? A. It
    will cause others to run. B. Running will put
    out the fire. C. The fire will burn out on
    its own. D. Running will feed oxygen to the
    fire.

Answer D
21
  • MSDS is a short way of saying A. Multiple
    standards data sheets. B. Material safety data
    sheets. C. Middle school deterioration status.
    D. Mastering school district safety.

Answer B
22
  • Laboratory aprons or coats should be worn when
    working with A. glassware of any kind. B.
    small animals when being handled. C. electrical
    equipment. D. chemicals and heated substances.

Answer D
23
  • Many chemicals are toxic. The best way to smell
    chemicals safely is to A. bring the container
    to your nose. B. inhale fumes directly from the
    container. C. ask your partner to smell the
    chemical. D. gently wave your hand over the
    container.

Answer D
24
Science Equipment and Taking Measurements
25
Quantity Instrument Units
Mass Balance Grams
Volume Graduated Cylinder Milliliters
Length Ruler Centimeters
Temperature Thermometer Degrees Celsius
Time Stopwatch Seconds
26
Triple beam Balance measures mass
Thermometer measures temperature
Graduated Cylinder measures volume
Stopwatch measures time
Meter stick measures length
27
Reagent Bottle
Florence Flask
Erlenmeyer Flask
Test Tube Rack
Test Tube Clamp / Holder
Test Tube
28
Watch Glass
Bunsen Burner
Alcohol Burner
Evaporating Dish
Petri Dish
Microscope
29
The Meniscus
  • When water is placed in a glass or plastic
    container the surface takes on a curved shape.
  • This curve is known as a meniscus. Volumetric
    glassware is calibrated such that reading the
    bottom of the meniscus, when it is viewed at eye
    level, will give accurate results.
  • Viewing the meniscus at any other angle will give
    inaccurate results.

30
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31
Erlenmeyer Flasks and Beakers
  • Erlenmeyer flasks and beakers are used for
    mixing, transporting, and reacting, but not for
    accurate measurements. The volumes stamped on the
    sides are approximate and accurate to within
    about 5.

32
Erlenmeyer Flasks and Beakers
33
Graduated Cylinders
  • Graduated cylinders are useful for measuring
    liquid volumes to within about 1. They are for
    general purpose use, but not for quantitative
    analysis. If greater accuracy is needed, use a
    pipet or volumetric flask.

34
Graduated Cylinders
35
Water Displacement Method
  • To determine the volume of a regularly shaped
    solid, the formulas from mathematics can be used.
  • To determine the volume of an irregularly shaped
    solid, the water displacement method is typically
    used.
  • A known amount of water is placed in a graduated
    cylinder.
  • The irregularly shaped solid is placed in the
    water.
  • The new volume is read.
  • The volume of the irregularly shaped object is
    the difference between the two readings.

36
Balances
  • Mass is the amount of matter in an object. There
    are different kinds of balances used to measure
    mass. Be sure you understand how your balance
    works. Some balances give a single reading.
    Others give two or more readings that you have to
    add together.

37
Balances
  • For example, look at the triple-beam balance on
    the next slide. Notice that the middle beam
    measures the largest amounts. To read the mass of
    an object, find and record the masses shown on
    each of the beams. Then add the readings.

38
  • 200g 70g 6.5g 276.5g

39
Metric Conversions
Kilo 1000 k 1000 times
Unit one one
deci 0.1 d One tenth
centi 0.01 c One one hundredth
milli 0.001 m One one thousandth
40
Graduated Cylinders
What is the volume?
About 36.3 ml (dont forget to read from the
bottom of the meniscus and to estimate a digit.
41
Triple Beam Balance
What is the mass?
356 g
42
Ruler
What is the length of the nail?
4.08 cm
43
Thermometer
What is the temperature?
47o C
44
The volume of the object is_________. A   8
mL B   11 mL C   16 mL D   21 mL E   27 mL
Answer B
45
  • A student needs to measure exactly 42.5 mL of an
    acid. Which of the following pieces of laboratory
    equipment would it be best for her to use?
  • 10-mL graduated cylinder
  • 50-mL beaker
  • 50-mL graduated cylinder
  • 250-mL flask

Answer C
46
Parts of an Experiment and the Scientific Method
47
Scientific Method
  • The scientific method is a systematic procedure
    for solving problems and exploring natural
    phenomena

48
Observations
  • 1. Observations (data) are the foundation of the
    scientific method . This observation might lead
    to a question regarding the event or
    characteristic. For example, you might drop a
    glass of water one day and observe it crashing to
    the floor near your feet. This observation might
    lead you to ask a question, "Why did the glass
    fall?"

49
Hypothesis
  • 2. Hypothesis In attempting to answer the
    question, a scientist will form a hypothesis (or
    some would say a guess) regarding the question's
    answer. In our example there are many possible
    hypotheses, but one hypothesis might be that an
    invisible force (gravity) pulled the glass to the
    floor.
  • A hypothesis is a tentative explanations designed
    to guide experimentation
  • A useful hypothesis must be testable and must be
    rejected or corrected when they conflict with
    experiment

50
Hypothesis
  • Notice that the hypothesis postulates a relation
    between the independent and dependent variable,
    one which produces the change, the other one in
    which the change is produced.
  • The hypothesis should fit well with what we
    already believe about the natural order of
    things.

51
Experimentation
  • 3. Experimentation Of all the steps in the
    scientific method, the one that truly separates
    science from other disciplines is the process of
    experimentation. In order to prove, or disprove,
    a hypothesis, a scientist will design an
    experiment to test the hypothesis. Over the
    centuries, many experiments have been designed to
    study the nature of gravity. Let's look at one.

52
Experimentation
  • In the late 16th century, it was generally
    believed that heavier objects would fall faster
    than lighter objects. The Italian scientist
    Galileo thought differently.
  • Galileo hypothesized that two objects would fall
    at the same rate regardless of their mass. Legend
    has it that in 1590, Galileo planned out an
    experiment. He climbed to the top of the Leaning
    Tower of Pisa and dropped several large objects
    from the top of the Leaning Tower.

53
Experimentation
  • What happens when you drop objects from the top
    of the tower? The two different objects fall at
    the same rate (as long as we ignore wind
    resistance).
  • Data can be qualitative or quantitative.
    Quantitative data is obtained by making a
    measurement. Qualitative is descriptive data.

54
Experimentation
  • Accuracy indicates how close a measurement is to
    the accepted value. For example, we'd expect a
    balance to read 100.00 grams if we placed a
    standard 100.00 g weight on the balance. If it
    does not, then the balance is inaccurate.
  • Precision indicates how close together or how
    repeatable the results are. A precise measuring
    instrument will give very nearly the same result
    each time it is used
  • Data is most useful when collected under
    controlled conditions (experiments).
  • Experiments must be repeatable and reproducible

55
  • The uncertainty of a measurement can be expressed
    in terms of accuracy or precision.

56
Relative Error
  • The accuracy of measurements can be determined by
    comparing your results with the accepted value.
  • The percentage error, or relative error, of a
    measured value can be found with the following
    equation

57
Develop a controlled experiment
  • Develop a controlled experiment Now we will take
    a closer look at what goes into making a
    "controlled" experiment.
  • variable - The quantities on which the outcome of
    an experiment depends are called variables.
  • dependent variable - this will be the single
    observation, or the result we will be observing .
    In reality one would observe as many dependent
    variables as possible.

58
Develop a controlled experiment
  • independent variable - this will be the single
    variable we elect to manipulate. All of the other
    variables must now be held constant so they don't
    influence our dependent variable. This way any
    change that occurs to the dependent variable can
    be attributed to our independent variable.
  • "control" - this will be the part of our
    experiment that does not receive the independent
    variable. This step is critical to the validity
    of a controlled experiment.
  • trials - Make sure sufficient data is gathered to
    form a conclusion. (more the better)

59
Develop a model or theory or Law Evaluate
Results
  • 4. Develop a model or theory or Law Evaluate
    Results
  • Galileo's experiment proved his hypothesis
    correct the acceleration of a falling object is
    independent of the object's mass. Why is this
    true? A few decades after Galileo, Sir Isaac
    Newton would show that acceleration depends upon
    both force and mass. While there is greater force
    acting on a larger object, this force is canceled
    out by the object's greater mass. Thus two
    objects will fall (actually they are pulled) to
    the earth at exactly the same rate.

60
Theories
  • A well-tested explanation for experimental data
    based on a set of hypotheses.
  • It must be discarded or refined when they can't
    explain new experimental results

61
Natural laws
  • Natural laws compactly summarize patterns in a
    large amount of data often apply only under
    special conditions
  • Natural laws are descriptions of nature, not
    explanations

62
Errors.
  • Errors are unavoidable in any experiment. No
    measurement is perfect.
  • Two kinds of error
  • random errors uncertainty of measurement, errors
    in reading a measurement, environmental factors
  • systematic errors-design of experiment, faulty
    equipment, false assumptions or simplifications

63
  • Fifty Chevy Camaros used only unleaded gasoline
    while another fifty Chevy Camaros used the same
    type of unleaded gasoline plus STP additive. The
    autos with the STP additive averaged 23 better
    gas mileage than the autos that did not receive
    the STP. In this experiment, the gas mileage is
    the _____ variable.
  • controlled
  • dependent
  • independent
  • manipulated

Answer B
64
  • An experiment needs to be designed to determine
    how changing the slope of the ramp affects the
    amount of time it takes a ball to roll to the
    bottom of the ramp. The best way to design this
    experiment is to _____.
  • change both the length and ball
  • change only the ball used
  • change only the height
  • change only the ramp surface
  • change the ramp surface and the height

Answer C
65
  • An investigation was conducted to determine how
    the amount of calcium chloride added to water
    affects the temperature of the water. In this
    experiment, the amount of calcium chloride is the
    _____ variable.
  • controlled
  • dependent
  • independent
  • responding

Answer C
66
  • An investigation was conducted to determine how
    the amount of magnesium sulfate added to water
    affects the temperature of the water. In this
    experiment, the temperature of the water is the
    _____ variable.
  • controlled
  • dependent
  • independent
  • manipulated

Answer B
67
  • To find out how much a person's weight changes in
    a year, you must know the _____.
  • gender of the person
  • person's weight at the beginning and end of a
    year
  • person's weight four years ago
  • type of food the person eats throughout the year
  • weight of the person's parents during the year

Answer B
68
  • A personal opinion that offers an explanation for
    an observation is a(n) _____.
  • dependent variable
  • experiment
  • hypothesis
  • independent variable
  • inference

Answer E
69
  • Mark watches a classmate kick his locker and says
    Boy, he must be mad at someone. Mark's
    statement is a(n) _____.
  • dependent variable
  • experiment
  • independent variable
  • inference
  • observation

Answer D
70
  • Josie walks outside at noon, notices the sky is
    dark gray and predicts that it will rain soon.
    Josie's prediction is a(n) _____.
  • dependent variable
  • experiment
  • independent variable
  • inference
  • observation

Answer D
71
  • Mickey has noticed that Karen wears a red shirt
    every Friday. This is an example of a(n) _____.
  • dependent variable
  • experiment
  • independent variable
  • inference
  • observation

Answer E
72
Other than the cup mentioned in the data table,
what laboratory equipment would you need to make
the necessary measurements? A   beaker, spring
scale B   beaker, triple beam balance C   graduat
ed cylinder, spring scale D   graduated cylinder,
triple beam balance E   test tube and triple
beam balance
Answer D
73
Tables and Graphs
74
Using Tables
  • Making observations and collecting information is
    large part of a scientists job.
  • Once this information is collected it must be
    organized and presented in a clear and concise
    way.
  • Tables and Graphs are the tools that scientists
    use to organize and present information.

75
Using Tables
  • Tables consist of horizontal rows and vertical
    columns of information.
  • Each row and column should have a heading that
    describes its contents.
  • The table itself should have a title to describe
    its purpose.
  • Identify the parts of the table on the following
    slide.

76
Using Tables
Column
Title
Heading
Row
77
Using Tables
  • A table can hold a lot of information.
  • Imagine how long it would take to write out all
    the information in this table in sentences.
  • A table allows you to present all of the
    information on a single page.

78
Using Tables
  • Tables organize data efficiently.
  • All of the data regarding problems with the video
    system is in a single row.
  • All of the data regardingsoftware related
    problems is in a single column.
  • The relationship between two variables is shown
    at the intersection of a row and column.
  • The number of hardware problems with peripheral
    components is shown at the intersection of the
    hardware column and the peripheral row.

79
Using Tables
  • Use the table to answer the following questions.
  • See if you notice a difference between the first
    two questions and the last two questions.

80
Using Tables
  • Which system has the most hardware problems?
  • Video
  • Users have the most difficulty with which system?
  • Peripherals

81
Using Tables
  • What percent of hardware problems relate to the
    drives and RAM?
  • 18.5
  • What would you do to decrease initial problems?
  • Send better instructions about the peripherals

82
Using Tables
  • How were the first two questions different from
    the last two?
  • The first two questions could be answered by
    reading directly from the table. The last two
    questions required you to make some calculations
    and judgments about the data in the table.
  • There is a lot more information in a table than
    what is written directly.
  • The information in a table can be interpreted in
    many ways to draw conclusions and make
    predictions.

83
Using Tables
  • Construct a table that can be used to compare the
    features of various models of lawnmowers.
  • The table should have a title and column and row
    headings. You dont need to put in the data.
    When you are done click to see an example.

84
Using Circle Graphs
  • While tables are used for organizing information,
    graphs are used to present information visually.
  • Different graphs are designed to present
    different types of information.
  • Circle graphs are best used to show how a whole
    is divided into its parts.

85
Using Circle Graphs
  • Circle graphs consist of wedge-shaped segments
    that together make a whole circle.
  • Each segment should have a name and a value.
  • The graph itself should have a title to describe
    its purpose.
  • Identify the parts of the graph on the following
    slide.

86
Using Circle Graphs
Title
Segment
Segment Name
Segment Value
87
Using Circle Graphs
  • Circle graphs are used to show how a whole is
    broken up into its parts.
  • In this case, the whole is the total number of
    students asked about their lunch preference.
  • The parts represent the 4 possible responses.

88
Using Circle Graphs
  • There are a few things you should notice about
    circle graphs.
  • The segments must add up to the total.

17 for hot dogs
20 for sandwiches
23 for hamburgers
40 for pizza
100 total
89
Using Circle Graphs
  • There are a few things you should notice about
    circle graphs.
  • The segment size must be relative to its value.
  • 20 (1/5) of students chose sandwiches so that
    segment is 1/5 of the circle.

90
Using Circle Graphs
  • Use the graph to answer the following questions.
  • See if you notice a difference between the first
    two questions, the next two questions, and the
    last question.

91
Using Circle Graphs
  • What percent prefer pizza or hamburgers?
  • 63
  • What is the least popular menu item?
  • Hot Dogs

92
Using Circle Graphs
  • If 500 students were surveyed, how many preferred
    hamburgers?
  • 115
  • How many students preferred sandwiches?
  • 100

93
Using Circle Graphs
  • Half the students (500 total) eat the school
    lunch every day. The other half will eat only
    when their favorite food is served. How many
    students can you expect to serve on pizza day?
  • 350 ( 250 ( 250 x 40 )) 350

94
Using Circle Graphs
  • How were the first two questions different from
    the next two? How was the last question
    different?
  • The first two questions could be answered by
    reading directly from the table. The next two
    questions required you to make some calculations
    and judgments about the data in the table. The
    answer to the last question was a prediction
    based on the circle graph.
  • The information in a graph can be used in many
    ways to draw conclusions and make predictions.

95
Using Circle Graphs
  • Construct a circle graph to show the following
    data about bald eagle populations in 1998
  • When you are done click to see an example.

96
Using Bar Graphs
  • While tables are used for organizing information,
    graphs are used to present information visually.
  • Different graphs are designed to present
    different types of information.
  • Bar graphs are best used to show how a number of
    objects or events compare in relationship to
    single property.

97
Using Bar Graphs
  • Bar graphs consist of a horizontal and vertical
    scale.
  • One scale identifies the objects to be compared
    the other scale is numerical.
  • The bar graph gets its name from the lines that
    identify the measured value of each object.
  • Identify the parts of the graph on the following
    slide.

98
Using Bar Graphs
Title
Numerical Scale
Label
Bar
Object Scale
Label
99
Using Bar Graphs
  • Bar graphs are used to compare measurements taken
    from a number of objects or categories.
  • In this case, the measurement is BTUs of energy
    consumption.
  • The categoriesare the differentfuel types.

100
Using Bar Graphs
  • There are a some important features of bar
    graphs. First, the numerical scale must be
    consistent
  • Each division on the vertical scale is one unit.
    On this graph 1 unit 1 quadrillion BTUs
  • Each division mustrepresent the same amount
    ofchange from thestart to the finish.

1 Quadrillion
1 Quadrillion
1 Quadrillion
101
Using Bar Graphs
  • The numerical scale must be consistent but there
    is no limit on the value you place on each
    division.
  • Our graph was redrawn with a different scale. Now
    1 unit 2 quadrillion BTUs
  • The scale is still consistent and the data is
    stillthe same but the graph looks different.

102
Using Bar Graphs
  • When each unit represents a larger value there
    appears to be less difference between the groups.
  • A graph can be misleading or difficult to read
    depending on the scale you choose.

103
Using Bar Graphs
  • Use the graph to answer the following questions.

104
Using Bar Graphs
  • How much total energy was used by households in
    1997?
  • 10.25 quadrillion BTUs

105
Using Bar Graphs
  • How many times as much natural gas is used
    compared to LP gas?
  • Over 14 times as much

106
Using Bar Graphs
  • In this graph, a second bar was added for each
    category with data from 1979.
  • This bar graph can then be used to compare the
    data from 2 different years.

107
Using Bar Graphs
  • What is the percent increase in total energy
    usage from 1979 to 1997?
  • About 5
  • What is the percent increase in electricity usage
    from 1979 to 1997.
  • About 46

108
Using Bar Graphs
  • From 79 to 97 theUS population increased by
    17, electricity consumptionincreased 46, yet
    household energy consumption increased only 5.
    How can you account for this?
  • The big increase in electricity use is probably
    related to the huge increase in electronic
    devices. The relatively small increase in total
    consumption is probably related to savings from
    more energy efficient devices.

109
Using Bar Graphs
  • Construct a bar graph to show the following data
    about US Endangered Animal Species
  • When you are done click to see an example.

110
Using Line Graphs
  • While tables are used for organizing information,
    graphs are used to present information visually.
  • Different graphs are designed to present
    different types of information.
  • Line graphs are best used to show a relationship
    between two measured quantities.

111
Using Line Graphs
  • Line graphs consist of a horizontal and vertical
    scale but both scales are numerical since each
    represents a measured quantity.
  • Line graphs are drawn by connecting observed
    points where the two numerical quantities
    intersect.
  • Identify the parts of the graph on the following
    slide.

112
Using Line Graphs
Title
Observed Points
Numerical Scale
Label
Numerical Scale
113
Using Line Graphs
  • Line graphs are used to compare two measured
    quantities.
  • In this case, the two quantities being compared
    are time and number of cell phone subscribers.
  • The dots represent the points at which actual
    measurementswere made.

114
Using Line Graphs
  • The points are located on the graph at the
    intersection of two measured quantities.
  • In 1994, there were 24.134 million cell phone
    subscribers. In 1996, there were 44.042 million.
  • Once the points are established a line is drawn
    to fit the data as well as possible.

115
Using Line Graphs
  • The number of cell phone subscribers was actually
    counted in 1984, 1986, 1988, etc.
  • But what was the count before 1984 or after 1998
    or in 1995?
  • A line graph can be used to make predictions when
    no actual measurements were made.

116
Using Line Graphs
  • To determine the number of cell phone subscribers
    in 1995, go up from 1995 to the line and over to
    vertical scale.
  • According to the line graph there were about
    33 million cell phone subscribers in 1995.
  • The line graph let us predict a value that we
    didnt actually measure.

117
Using Line Graphs
  • To predict the number of cell phone subscribers
    in 1999, you must extend the line then go up from
    1999 and over to the vertical scale.
  • According to the line graph there may be about
    85 million cell phone subscribers in 1999.
  • How is the 1999 prediction different from the
    1995 prediction?

118
Using Line Graphs
  • The 1995 prediction occurred between 2 measured
    points.
  • The 1999 prediction occurred after the last
    actual measurement.
  • In which prediction do you have the most
    confidence?

119
Using Line Graphs
  • The 1995 prediction is more reliable because we
    know what happened before and after. However, we
    dont know what happened after 1998.
  • After 1998, cell phone subscriptions may continue
    to increase which is what we assumed.

?
  • They may level off.
  • They may decline.
  • We cant be sure what will happen after 1998.

120
Using Line Graphs
  • How many cell phone subscribers were there in
    1991?
  • About 8 million
  • In what year did the number of subscribers hit
    55 million?
  • In 1997

121
Using Line Graphs
  • Construct a line graph to show the following data
    about the percent of US high school dropouts

1975 13.9 1980 14.1 1985 12.6 1990 12.1 1995 10.5
  • When you are done click to see an example.

122
Using Line Graphs
  • Match the type of graph with its use.

Used to compare several categories Shows the
relationship between two measured
quantities Shows a single measurement of a number
objects or events Shows how a whole is divided
into its parts. Used to make predictions and show
trends
Circle Graph Bar Graph Line Graph
123
(No Transcript)
124
What does the graph indicate about the
relationship between distance and time? A   As
time decreases, distance increases. B   As time
increases, distance decreases. C   As time
increases, distance increases. D   Distance
remains constant while time increases. E   Time
remains constant while distance increases.
Answer C
125
  • After 7 seconds had passed, the temperature of
    the substance was approximately _____ degrees
    Celsius?
  • 4
  • 7
  • 10
  • 14
  • 20

Answer D
126
Temp (oC) Humidity Amount of mold after 2 weeks
0 Low None
0 High None
5.5 Low Small Amount
5.5 High Medium Amount
25.5 Low Medium Amount
25.5 High High Amount
  • According to the data, what are the best
    conditions for growing mold?
  • cold temperature and low humidity
  • warm temperature and low humidity
  • cold temperature and high humidity
  • warm temperature and high humidity

Answer D
127
  • Paramecium caudatum was cultured first.
    Parameciumc aurelia was added to the same culture
    one day later. According to the graph, which is
    the first day that P. aurelia will exist alone in
    the culture medium if the trend shown continues?
  • Day 12
  • Day 13
  • Day 16
  • Day 18

Answer B
128
Answer A
  • According to the graph, what would most likely
    happen to bluegill sunfish if the temperature of
    the water in which they live were to rise above
    27C for a period of two weeks?
  • The rate of ventilation would slow, and the fish
    would die of thermal shock.
  • The rate of ventilation would increase to
    counteract low oxygen levels.
  • The rate of ventilation would remain constant as
    the fish adapt to warmer water.
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