In your groups make your own list of questions. Which group can come up

with the most?

• Questions Science can

answer

• Questions Science can’t

answer

Scientific MethodScientific Method

Origin / Context• It is a method used to understand the world,

not a mountain of ‘facts’• Science cannot provide certain (100%) proof –

just the ‘best’ working theories• Science is from the Latin “scientia”, which

means knowledge• First developed by Francis Bacon 17th C• It is a trial and error process• Allows us to systematically examine the

processes behind natural phenomena, and make predictions and laws regarding these.

Beginnings• Aristotle • (384 BCE-322 BCE or

BC) ancient Greek philosopher

• Aristotle was so famous that his work influenced thinking in the Western world from his time to the present.

• This was fine when he was right. But he was so influential that his mistakes were never noticed.

• Aristotle and his contemporaries believed that all problems could be solved by thinking about them.

• Sometimes this worked, other times it did not.

• For example, Aristotle thought that heavy objects would fall faster than lighter ones.

• Now that does seem reasonable at first. And this is how “science” was done in ancient times.

• But what did Aristotle not do?• He never tested his ideas!• The world would have to wait

almost 2000 years for that to happen.

Galileo Galilei•1564-1642 AD or CE

•Is considered to be the first true scientist.

•Why????•Because he actually did

the experiment.

• Aristotle said that heavy objects fall faster than lighter ones.

• So Galileo asked, “How much faster?”

• So he sent students up to the top of a building and had them drop a heavy ball and a lighter one off at the same time. He had other students waiting below to measure the difference in time between the two hitting the ground.

• Today of course we know what happened. Much to everyone’s surprise both balls hit the ground at about the same time!

• This shows that it is much preferred to test your ideas rather than merely think about them.

Key Idea• When conducting an experiment,

change one factor and keep everything else exactly the same.

• The one thing you change is called the variable.

• All the things you keep the same are called controls.

Galileo’s Experiment• What was the variable in Galileo’s

experiment?• The weight of the balls.• What were some controls?• Dropped from same height.• Dropped at same time.• Balls had same shape/size.

Scientific Method Steps• State the problem.• Make a hypothesis.• Conduct the experiment.• Record/analyze data.• Make a conclusion.• Report findings to others so they can

repeat the experiment.

Observations• Observations: We use our senses

to gather information about the world around us.

Hypothesis• An educated guess• a prediction• Use “If”, “then” format• We predict that if we drop a ball from a

higher height, then it will bounce higher.• “If” is the manipulated variable.• “Then” is the responding variable.

Theory• Has a very different meaning in

science than in everyday life.• “The detective has a theory about

who robbed the bank.” This is a guess.

• When scientists use the word theory it is not used as a guess.

• So the theory of gravity, theory of electricity, the germ theory of disease, and the theory of evolution are tested, accepted explanations for events that occur in nature.

• Theories can really never be completely proven, only disproven. When new evidence comes along, we must modify our theory or at times even get rid of it and start over again.

• Ptolemy’s earth centered theory of the solar system is an example of what can happen when new evidence comes along.

• When Copernicus showed that putting the Sun in the center made it much easier to predict the planets motions, the old earth centered theory was discarded and a new one developed.

Scientific MethodScientific Method

Scientific Method Further Explained

• The particular version of scientific method we have looked at so far is called the inductive method. Here we go from general observations to specific theories then scientific laws through a process of testing, retesting and verifying our hypotheses. If the evidence that we gather fits our hypothesis then our hypothesis is supported (never proved). If the evidence seems to go against our hypothesis then we might try refining the tests we use , if we’re still convinced that our hypothesis is true to see if it makes any difference.

There might come a time where we will have to abandon or reject our hypothesis because the evidence does not support it.

• This means that scientific ‘facts’ are always open to the possibility that new evidence will bring them into question – or perhaps new ways of understanding the old evidence.

• That’s what science is in fact, it is a process rather than a destination, a method rather than a set of facts to be learned.

Strengths and Limitations• The method is an effective

way to follow up observations with systematic testing.

• It takes into account alternative possibilities and puts these to the test.

• It produces testable hypothesis.

• It can be verified or falsified.• It leads to laws and theories,

which cover all similar instances.

• The method can be replicated by others and so our findings supported or rejected.

• We have to begin by observing and sometimes we might not ‘see’ anything worth testing – its still open to interpretation.

• We need to be sure that all possible alternatives were considered.

• Hypothesis reached might still be based on our interpretation of what we observe and so may be an inaccurate or misleading starting point.

• What counts as verified or falsified is still subject to our interpretation of the evidence.

• Exact replication of any scientific research may not always be possible due to errors and differences in the environment of testing etc.

• Objectivity – is one of the most important principles within the scientific method. Scientists and science have to test and conclude based on evidence they discover. If it goes against their hypothesis then so be it!!

• Now of course this isn’t easy. It might mean rejection of some scientist life's work, it might mean going against scientists considered great. It might mean rewriting every science book in existence.

Scientifically proven!!!

• How many TV adverts claim to have a product that is scientifically proven?

• It might be that it kills 99% of germs or 8/10 hamsters prefer this type of food – or this reverses the sign of ageing or help you lose weight on a diet of ice cream and chocolate..

The Stages1. Observation: ‘Finding’ something in nature

that you want to find answers to2. Hypothesis: An educated guess as to what is

going on in the observable phenomenon3. Experiment: Controlled examination of

evidence and testing of the hypothesis4. Verification: Results from the experiment can

help to reinforce the hypothesis, which can continue to be examined and verified by others, or proved to be false, in which case you start again. This process of trying to find fault with a theory to make sure it is more reliable is called falsification.

Strengths and Weaknesses1. Scientific Method should be

rational, and examined in a controlled and objective way = trustworthy

2. Theories are continually tested and modified, so we know they are the best they can be

3. It provides us with a way of understanding our world and predicting events – with this we can progress in science and technology

1. It is NOT objective: scientists are humans with ambitions, personalities, and who need to INTERPRET data

2. It will NEVER give us 100% proof because it is a process of INDUCTION.

3. It can only tell us about the processes behind events – it cannot give us information on the reason behind why things are the way they are.

4. It cannot talk about anything other than physical phenomena – issues of morality, philosophy and religion are outwith scientific enquiry

1. What is the scientific method?2. Why are scientists cautious about

saying that they have proved something?

3. Explain one strength and limitation of the scientific method.

3. ‘The scientific method is the best way to work out what is true.’ Do you agree? Give two reasons for your answer.

In what ways is the scientific method limited?

It is fallible.Limited objectivity.Scientist is human.Based on assumptions.More to the world than

the observable.Contains guesswork.Reliability.Tentative

1. Why are scientists cautious about saying that they have proved something?

2. ‘The scientific method is

the best way to work out what is true.’ Do you agree? Give two reasons for your answer.