QOTD 9/9/14

1. Pick up a safety quiz (do not write on it!) and an answer sheet. Take the quiz- 10 minute time limit!

2. Return the quiz and your answer key. Pick up a “clicker”.

3. Find your response to yesterday’s QOTD (“doing science”).

Use the clicker to input your choice: A, for Antoine, B for Tamara, C for Marcos, or D for Avery.

Learning Targets

• Be able to distinguish between an observation and an inference• Be able to describe how science is done • Be able to describe the “scientific method”

How science works• How science works: not just experiments https://

www.youtube.com/watch?v=Jj9iNphbY88 (6 min) California Academy of Sciences

• Thinking like a scientist: number pattern https://www.youtube.com/watch?v=vKA4w2O61Xo&list=PL16649CCE7EFA8B2F (5 min) Veritasium

SCIENTIFIC METHODSend a group member to get a notes sheet for each group member.

SCIENTIFIC METHOD• The scientific method is an

organized way to solve a problem or answer a question.

• You probably use it every day without even thinking about it.

• It is NOT a “follow the steps” method; but often we can do science by following some generalized steps…

The Problem or Question

•What do you want to find out? What problem are you trying to solve?• State your problem or purpose as

clearly as possible.• Does your problem have more than

one part?

Observations / Research• An observation is when you use your

senses to gather information about your problem.• Use your past experiences as a

resource.• Research is an important part of

gathering information.

• Quantitaitve = numbers/measurement• Qualitiative = quality, color, etc.

Observation vs. Inference• An inference is a conclusion reached based

on evidence or reasoning. • Be careful not to confuse an observation

with an inference!

• For example: • There is a long line at the restaurant. This

is an observation.• The food is good at the restaurant. This is

an inference.

Observations and Inferencesidentify each statement as either a qualitative observation or

quantitative observation, or as an inference. - You have 3 minutes…1. Linus is looking at the puddle of water.

2. Linus is thinking as he studies the puddle.

3. Linus stomps angrily on the puddle.

4. Some water evaporated from the puddle.

5. Linus produced more than 6 small puddles when he stomped.

6. None of the puddles are the same size as the original.

7. If all the puddles were recombined, it would be the same size as the original puddle.

Qualitative observation – can’t be measured

inference

inference

inference

Quantitative observation – counting

Quantitative observation – you can measure the size

inference

Scientific Hypothesis• A possible solution to the problem based

on your observations, research, and past experience.

Allows you to make a prediction: “If ___X___, then _______Y____ will happen because __Z____”

• Often called “educated guess”, but this is not a good definition! A good hypothesis is much more than just a guess!

Hypothesis•Must be testable and falsifiable. If it is

impossible to test your guess or prove that it is false, then it is NOT a scientific hypothesis!• testable example: “Cactus spines reduce the

amount of damage caused plant eaters”

• “if we remove the spines of some cacti, then more of them will be eaten” – we CAN test this!

Hypothesis non-example

• untestable example: anything involving supernatural forces, morality, religion, etc. (spirits, psychics, ghosts, God, etc.)

• Science ONLY deals with the natural world and can ONLY answer testable and falsifiable questions!

Experiment• An scientific experiment is a way

to test a hypothesis.• Either proves the hypothesis

wrong (falsifies it) or it supports the hypothesis.• An experiment NEVER proves the

hypothesis right!

Experiment (cont’d)

• A variable is a factor that can be changed in an experiment.• Independent (manipulated) variable –

what you change on purpose• Dependent (responding) variable – what

happens as a result of changing the independent variable

• A control variable remains the same during the entire experiment.

A Controlled Experiment

• For an experiment to be valid, it must be controlled.• During a controlled experiment only one

variable is changed at a time.• The scientist must contrast an

experimental group with a control group. The two groups are treated EXACTLY alike except for the ONE variable being tested.

Replication, sample size, and reliability

• Procedure is repeated several times to see if results are consistent.

• Results from different trials are averaged.

• Often large numbers of trials or large samples are taken.•More replication and large sample size = more

confidence in the result

• A reliable experiment is one that is done in the same way each time and gets the same results.

Results

•Make necessary graphs

• Analyze the results. Do they make sense?

Conclusion• Was your hypothesis supported or

falsified?• What did your experiments tell you?

Do you need to do further experiments? • If your hypothesis was not supported,

you would change your hypothesis and do a new experiment.

• If your hypothesis was supported, it does NOT mean you were correct! It just means you might not be wrong! Other experiments might show that you weren’t right after all!