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Chapter 1.3-1.5Scientific Method

Mrs. BaldessariChemistry

Objective : Identify and apply the steps of the scientific method.

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–The goal of science is to:• investigate and understand the natural

world.• explain events in the natural world.• use those explanations to make useful

predictions.

What is the goal of science?What is the goal of science?

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Thinking Like a ScientistThinking Like a ScientistScientific thinking begins with observation.Scientific thinking begins with observation.

• Observation is the process of gathering information about events or processes in a careful, orderly way

• Use your senses to observe–See, hear, touch, taste, smell, etc.

• Can also use tools to measure–Temperature, length, volume, etc.

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What are the steps of the scientific method?

1. Define the problema. Select an event or phenomenon for

investigation.b. The problem is often based on some type

of unexplainable observation.c. The problem is usually stated as a question

to be answered.

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What are the steps of the scientific method?

2. Gather relevant researcha. The researcher gathers useful information

from scientific literature.b. Observations of the problem may also

contribute to research.

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What are the steps of the scientific method?

3. Formulate a hypothesis• A hypothesis is an “educated guess” about the answer to

the problem.• The hypothesis is based on information, which has been

learned about the problem through research.

• May be stated as an “If…., then…” statement • A hypothesis may be ruled out or confirmed.

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What are the steps of the scientific method?

4. Test the hypothesis• A hypothesis must be proposed in a way that can be

tested. • Hypotheses are tested by performing controlled

experiments or by gathering new data.• Remember, controlled experiments are experiments

that only have one variable that can change, all other factors are held constant

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What are the steps of the scientific method?

5. Record data and observations• The information gathered from observations is

called data.• Quantitative data are expressed as numbers,

obtained by counting or measuring.• Qualitative data are descriptive and involve

characteristics that can’t easily be measured.

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• Look around the room list Five Quantitative observations:

• 1.

• 2.

• 3.

• 4.

• 5.11

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• Look around the room list Five Qualitative observations:

• 1.

• 2.

• 3.

• 4.

• 5.

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Inferences

• Scientists use data to make inferences.• An inference is a logical interpretation based

on prior knowledge or experience.• Is this an observation or inference?• 1. Sam is smiling because he is happy• 2. Sarah’s gold colored braces were

removed today

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You try: Observation or inference?

• Object A is round

• Object A is a basketball

• Object C is round and black and white

• Object C is larger than object B

• Object B is smooth

• Object B is a ping-pong ball

• Each object is used in a different sport

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Observation or inference

• Object A is round

• Object A is a basketball

• Object C is round and black and white

• Object C is larger than object B

• Object B is smooth

• Object B is a ping-pong ball

• Each object is used in a different sport

• A is a basketball; B is a ping-pong ball; C is a soccer ball

O I

xx

x

x

x

xx x

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Designing an Experiment with

TwinkiesDiscussion of independent

variables and control variables

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What is the control?What is the independent variable?

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Control

• Is an experimental set-up with all the parts of the experiment BUT NOT the one variable being tested

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What is the independent variable?

What might a control be?

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What is the independent variable?

What might a control be?

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Identify Variable and the control:

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To get all the air out, the twinkie was “liquified.”

So which side is the control?

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What are the steps of the scientific method?

6. Draw conclusions• Researchers often work in teams to analyze, review, and

critique each other’s data and hypotheses.• A review process helps ensure conclusions are valid.• To be valid, a conclusion must be based on logical

interpretation of reliable data.• Always address sources of error…are your results

legitimate?• Theories and laws are heavily supported by

experimental results

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Copyright © by McDougal Copyright © by McDougal Littell. All rights reserved.Littell. All rights reserved. 2222

Figure1.1: The

various parts of

the scientific method.

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Science is an ongoing process that involves:

–asking questions–observing–making inferences–testing hypotheses

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State the Question

•“What is the effect of…”

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Hypothesis

• “If…then…” If I diligently wear my goggles in the lab, then I will not injure my eyes during Chemistry class this year.

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Experiment

• Independent Variable -what you change goes on the X-axis of the graph

Dependent Variable -what changes as a result of what you did – goes on the Y-axis of the graph

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Independent Variable?Dependent Variable?

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Experiment

• Constants-all the things in the experiment that stay the same

• In a Twinkie lab :same brand of Twinkies

same flavor of Twinkies same degree of freshness

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Experiment

• Control – the part of the experiment that does not have the independent variable in it

• In a Twinkie lab, it could be the room temperature

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Experiment

Record the datagraphs charts

video write observations measurements

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Conclusion

• Agree or disagree with the hypothesis

• Goggles did protect my eyes during an accident

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Scientific method

Do background Research

Record Results

Analyze Results

Draw a conclusion

Present results

State your question or the problem

Formulate a hypothesis, identify variables

Design a Controlled Experiment, establish a procedure

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Science as a Way of Knowing

• Scientific understanding is always changing. • Good scientists are skeptics who question

both existing ideas and new hypotheses.

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1–1

Observations involving numbers are known as

a. qualitative observations.

b. hypothetical observations.

c. quantitative observations.

d. inferred observations.

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1–1

A scientist takes paint chips from 10 apartments in a large building. She tests for the presence of lead in the paint and finds it in all 10 samples. She then concludes that lead paint is probably present in all 120 apartments in the building. This conclusion is an example of

a. a scientific fact.

b. a scientific error.

c. proof.

d. a reasonable inference.

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1–1

A possible explanation for a set of observations is known as

a. data.

b. a hypothesis.

c. an inference.

d. a result.

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1–1

A good scientific hypothesis must be

a. correct.

b. able to be tested.

c. obvious.

d. based on common sense.

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