Scientific Method Qualitative vs quantitative

observations Correct hypothesis statements Types of graphs Basic metric system units Histograms and scatter plots

This class usees the 5 step This class usees the 5 step Scientific Method : Scientific Method : Observation/Question Observation/Question HypothesisHypothesisExperimentExperimentResultResultConclusionConclusion

The batteries

correct…

WHO AMONG US HAS NOT

HAD THIS VERY EXPERIENCE?

This is the scientific method in action.

Color, shape, feel, taste, sound.

EXAMPLES:o Leaves are big and shinyo Flower is blue.

Quantity: How many. Will always have a number. Based on exact measurement.

EXAMPLES:o Ave leaf size is 10cm. o There 18 leaves vs10 leaves.

Hypothesis

-• A testable prediction • Based on your observations. • Is testable with an EXPERIMENT. • Uses If…. Then….

Use “If”, _________________(IV)_“Then” Use “If”, _________________(IV)_“Then” _____________________(DV)__format_____________________(DV)__format

IfIf we drop a ball from a higher we drop a ball from a higher height, height, ThenThen it will bounce higher. it will bounce higher.

› ““If” is the Independent If” is the Independent variable. (IV)variable. (IV)

› ““Then” is the dependent or Then” is the dependent or responding variable. (DV)responding variable. (DV)

Use “If”, Use “If”, _________________(IV)_“Then” _________________(IV)_“Then” _____________________(DV)__form_____________________(DV)__formatat

Makes a predictionMakes a prediction Can be tested by an Can be tested by an

experimentexperiment

HYPOTHESISHYPOTHESISIf I add fertilizer If I add fertilizer

to my plant to my plant then it will grow then it will grow taller than the taller than the

same plant same plant without without fertilizerfertilizer

OBSERVATIOOBSERVATIONN

Some plants Some plants are taller are taller

than othersthan others

CONTROL GROUPreceives “normal” treatment

EXPERIMENTAL GROUPreceives independent variable

Plant will get:• sunlight• water• soil

Plant will get:• sunlight• water• soil • fertilizer

A controlled experiment is a comparison of A controlled experiment is a comparison of two or more groups with two or more groups with one differenceone difference

between the groupsbetween the groups

sunlight, sunlight, water, water, soilsoil

CONSTANT VARIABLE: CONSTANT VARIABLE: factors that stay the factors that stay the samesame

INDEPENDENT VARIABLE:INDEPENDENT VARIABLE: the difference between the groups; the difference between the groups; the factor manipulated (changed) by the the factor manipulated (changed) by the experimenterexperimenter

fertilizfertilizerer

DEPENDENT VARIABLE:DEPENDENT VARIABLE:the measured result of the the measured result of the experiment; experiment; the factor that responds to the the factor that responds to the changechange

plant plant heightheight

What is being measured

Units used(abbreviated)

Tool used to measure

Example

LENGTH Meters (m)Kilometers km(1000 meters)

Meter stick Length of my nails, distance from Chicago to NY city

VOLUME Liters (L)Milliliters mL(1/1000 liters)

Graduated cylinder

Amount of liquid in a can of coke, amount of cough medicine in a teaspoon

MASS Grams (g)Kilograms kg(1000 grams)

scale How much weight I lost last summer, how much these bananas weigh

Graphing: What kind of graph should I use?

1. Variability within a group? frequency plots frequency plot

2. Compare groups? bar graph

3. Change through time? line graph

4. Correlation between 2 things? scatter plot

• TITLE (Effect of ______ (IV) on __________(DV)

• AXIS LABELS (with units)• INTERVALS (are even)• LEGEND/Key (explains any symbols)• SCALE (scale is proportional)

5 ELEMENTS OF ALL GRAPHS

DRY

MIX

(DependentRespondingY axis)

(IndependentManipulatedX axis)

BAR GRAPH

Title

Key or Ledger

Labels

Y a

xis

X axis

Bar graphs compare groups NO relationship between groups Data is NOT continuous Examples

› Rainfall by month› Which candy students like

Line graphs show TRENDS There IS a relationship DATA is continuous

› You can go between the points and get a piece of data that is meaningful (interpolate)

Examples› Baby’s growth vs age› Test scores vs study time› Football touchdowns vs practice time

2005-2006

2005-2006

Is there a correlationBetween husband and

wife’s age?

Yes there is a STRONGPOSITIVE

CORRELATION

Scatter plots

2005-2006

Is there a correlationBetween a person’s height and math test

scores?

NO! There is noCorrelation between

height and math scores on the test

Scatter plots

Person’s Height (ft)

Mat

h t

est

sco

res