Use the ACT passage on your desk to answer the following questions:

1. About which of the following points do the two theories differ? A. Movement of tectonic plates across the Earth’s surface B. Density of hot mantle rocks C. Existence of convection currents in the Earth’s mantle D. Role of mantle convection in tectonic plate movement

2. How would supporters of Slab Pull Theory explain the documentation of seafloor spreading cited in Mantle Convection Theory? A. Seafloor spreading directly causes tectonic plate movement and slab subduction.B. Seafloor spreading does not exist. C. Seafloor spreading and slab subduction simultaneously exert moving forces on tectonic plates. D. Seafloor spreading exists, but only as a result of slab subduction.

Catalyst: 9/14/10

ObjectiveSWBAT… List and describe the steps of the scientific method

Agenda-Catalyst (7)-Scientific method Powerpoint notes (25)-Scientific method sequencing (15)

HomeworkSection 2 Review, page 53, even numbers

The Scientific Method involves a series of steps that are used

to investigate a natural occurrence.

The Scientific Method1. Observe an event.2. Develop a model (or hypothesis) which makes

a prediction.3. Test the prediction

(experiment).4. Observe the result.5. Revise the hypothesis.6. Repeat as needed.7. Publish/Present*

model

test

ObservationsObservations

• Gathered through Gathered through your your sensessenses

• A scientist notices A scientist notices something in their something in their

natural worldnatural world

HypothesisHypothesis

• A suggested solution to A suggested solution to the problem.the problem.• Must be Must be testabletestable• Sometimes written as Sometimes written as

If…Then…If…Then… statements statements• PredictsPredicts an outcome an outcome

ExperimentExperiment

• Develop and follow a procedure to to testtest the the

hypothesishypothesis.• Include a detailed

materials list.• The outcome must be

measurable (quantifiable).

Scientific Experiments Follow Scientific Experiments Follow RulesRules

• An experimenter changes one factor and observes or measures what happens.

Variables

• The factor that is changed is known as the independent variable. • The factor that is

measured or observed is called the dependent variable.

The Control VariableThe Control Variable

• The experimenter makes a special The experimenter makes a special effort to keep effort to keep other factors constantother factors constant so that they will not affect the so that they will not affect the outcome.outcome.• Those factors are called Those factors are called control control

variables.variables.

What is the Purpose of a What is the Purpose of a Control?Control?

• Controls are NOT being tested• Controls are used for COMPARISON

Control Group The control group is exposed to the same conditions as the experimental group, except

for the variable being tested.

Example of Controls & Example of Controls & VariablesVariables

• For example, suppose you want to figure out the fastest route to walk home from school.

• You will try several different routes and time how long it takes you to get home by each one.

• Since you are only interested in finding a route that is fastest for you, you will do the walking yourself.

What are the Variables in What are the Variables in Your Experiment?Your Experiment?

• Varying the route is the Varying the route is the independent variableindependent variable • The time it takes is the The time it takes is the

dependent variabledependent variable • Keeping the same walker Keeping the same walker

throughout makes the throughout makes the walker a walker a control variable.control variable.

One more thing… it is best to make several trials with each

independent variable.

DataData

• Results of the experiment• May be quantitative

(numbers) or qualitative (descriptive)

DataData

• Must be organized• Can be organized into

charts, tables, or graphs• Must be analyzed to

determine whether to accept or reject hypothesis

ConclusionConclusion• Include a statement that

accepts or rejects the hypothesis.• Make recommendations

for further study and possible improvements to the procedure.

Determine Limitations to Revise

• Scientists look for possible flaws in their research

• They look for faulty (inaccurate) data

• They look for experimental error or biases

• They decide on the validity of their results

• They make suggestions for improvement or raise new questions

RetestRetest

In order to verify the results, experiments must be

retested.

Medical ScienceScientific Method

High Cholesterol

Observation Patient has high cholesterol

Hypothesis (prediction)

Certain chemicals may dissolve cholesterol deposits.

Test Give 100 patients these chemicals, give 100 patients placebo.

Observe result Same number lower their cholesterol as placebo patients.

Revise hypothesis?

Try different combo of chemicals.

New test? Re-run medical test. Observe results.

Scientific Theory

Lipitor reduces cholesterol.

Everyday Science

Scientific Method Making Spaghetti Sauce

Observation Spaghetti sauce should be red.

Hypothesis (prediction)

Try a tomato sauce.

Test Heat pot of tomato sauce.

Observe result Taste the sauce - bland.

Revise hypothesis? Use tomato sauce and garlic!

New test? Add garlic, taste - not so bland.

Scientific Theory The Final Recipe.

Theories

• A theory is a highly successful hypothesis.

• All theories make predictions which can be tested.

• Any scientific theory can be falsified and is subject to change as our ability to make tests, or make observations of a test’s results, improves with time.

Non-scientific Theories

• Make no predictions• Cannot be tested • Cannot be falsified

Scientific Method Sequencing• Take out your “Record Sheet”• I will pass out envelopes with cards inside with the

steps of experiments• Put the cards into the correct order

(Question, Hypothesis, Experiment, Data, Conclusion)• Write the letter of the card which fits each part for that

experiment (e.g., headache holly goes in the first list)• When finished, shuffle the cards.• Swap envelopes until you finish all 6 experiments.

Remember… Homework: pg 53 questions, even only