Thinking like a Scientist

Science is an organized way of using evidence to learn about the natural world. The word science also refers to the body of knowledge that scientists have built up after years of using this process.

What is the goal of science? 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.

Thinking Like a Scientist Scientific thinking begins with observation. Observation is the process of gathering information about events or processes in a careful, orderly, accurate and objective way. Accurate: exact report of what your senses tell you Objective: avoids opinions (or bias) based on a previously held point of view (just the facts, please) Name our 5 senses:

Observation vs. Opinion Science is about facts, not opinions Saying a dress is red is a fact red is observable with your senses, red is always the same Saying a dress is pretty is an opinion everyone likes different types of dresses so pretty is different for different people

The information gathered by observations or experiments is called data. QuaNtitative data: expressed as Numbers, obtained by counting or measuring Qualitative data: descriptive words (adjectives) used and involves characteristics that aren’t or can’t easily be measured QuaNtitative: 8 zebras are in this picture Qualitative: most zebras are looking to the right

Types of Observations QuaNtitative observations–numbers involved e.g. he is 7 feet 1 inch Qualitative observations- words involved e.g. he is very tall

Scientists use data to make inferences. Inference: logical interpretation based on observations, prior knowledge, experience or opinions; attempted explanations or conclusions based on data gathered from observations; or any type of thinking process done from observations Observation is what you see (or hear, etc.) Inference is what you figure out Example: Testing water by checking small amounts, called samples, may allow the scientist to infer all the water is safe.

Scientists make predictions. Predictions: use of knowledge to explain what might happen in the future Example: Since the water has tested safe, I predict that no one will die from drinking it.

Warm up: Write 3 observations and make one inference about this picture Observation is what you see (or hear, etc.) Inference is what you figure out

Science is involved in solving problems in the natural world Solving any problem requires organization. In science, this organization often takes the form of a series of procedures referred to as the scientific method.

Scientific Method: Common procedures used by scientists to gather information used in problem solving and experimentation.

Steps of the Scientific Method: State the Problem (Ask a Question) & do some research Gather Information-learn more Form a Hypothesis-testable prediction

Steps of the Scientific Method: 4) Perform an Experiment-(Yeah, labs!) 5) Analyze Data-review the facts learned during the experiment 6) Draw Conclusions-after it’s all done, what did you learn from the experiment? Models are created to help see (or visualize) ideas in a way that’s easier to work from e.g. globes of Earth, drawings of cells, etc.

Observation: using our senses to collect or bring together information State the Problem or Ask a Question: It starts when you ask a question about something that you observe (How, What, When, Who, Which, Why, or Where?) Observation: using our senses to collect or bring together information What are your senses, anyway?

Gather Information: Do background research. Form a Hypothesis: A question that can be tested.

A hypothesis is a proposed scientific explanation for a set of observations. A hypothesis may be ruled out as not true or found to be correct (confirmed as valid) A hypothesis must be proposed in a way that can be tested. Hypotheses are tested by performing controlled experiments or by gathering new data. A hypothesis must be tested by doing experiments or more observations before we know for sure that it is true

Example: How do organisms come into being? Many years ago, people wanted to know how living things came into existence or how they started living or growing. They started with a question that asked: How do organisms come into being?

One early hypothesis was spontaneous generation, or the idea that life could come from nonliving matter. For example, most people thought that maggots spontaneously appeared on meat. Hypothesis: testable question or prediction; “educated guess” People used to think that maggots appeared spontaneously or suddenly, all by themselves, almost by magic

Maggots- white worm like creators that later become flys

Francisco Redi observed that maggots appeared on meat a few days after flies were present. In 1668 he proposed a new & different hypothesis: that maggots came from eggs that flies laid on meat. Hypothesis: explanation to observations that might be true, it must be tested by more observations or by doing experiments before we know for sure that it is true

Perform an Experiment: A series of steps are followed to test a hypothesis using controlled conditions.

Controlled Experiment: experiment in which no more than two variables are changed at a time Variable: Something (a factor, a part of) in an experiment that is changed (e.g. type of insect tested, type of food, location, temperature, time spent on experiment, etc.) (e.g. = for example, etc. = more examples)

What would happen if you changed too many variables at once? e.g. different temperatures, different types of food for the maggots to grow in, different lengths of time spent for testing You would not know which variable caused the results you get. It’s a bad idea to have some maggots grown on carrots in your kitchen for one day, some grown on meat laying in snow for one week, some grown on oatmeal in the dessert for one month. Too many variables make things too confusing. Two variables (one you change- or control- and one you measure) lets you know exactly what caused the effect you’re measuring

Independent variable (manipulated variable): factor in an experiment that a scientist purposely changes or controls e.g. covered or not covered jars Dependent variable (responding variable): factor in an experiment that a scientist wants to observe or measure, it may change in response to the independent variable e.g. how many, if any, maggots appear Constants (controlled) variable: factors in an experiment that a scientist purposely keeps the same Time, temperature, type of food, etc.

Independent variable (manipulated variable): scientist changes Dependent variable (responding variable): it changes because of what happens during the experiment

Redi’s Experiment Uncovered jars Covered jars Controlled Variables: Same jars, type of meat, location, temperature, same length of time, etc. Good hypothesis: If flies land on meat, then maggots will be made because maggots are made from flies.

Redi’s Experiment Manipulated Variable: Several days pass. Gauze covering that keeps flies away from meat Several days pass. Responding Variable: whether maggots appear Maggots appear. No maggots appear.

Experimental & Control Groups Experimental Group: Group being tested This group experiences the manipulated variable (the one scientists change in the experiment) Control Group: Used as a comparison group This group does NOT have the manipulated variable but it does have (experience) all the other parts of the experiment (constants or controlled variable)

Experimental and Control Groups

Analyze Data: See if your data supports your hypothesis

Draw conclusions: A conclusion is a logical answer to a question (hypothesis) based on data and observations

Researchers often work in teams to analyze, review, and check (critique) each other’s work, including conclusions from experiments

Why would they want to do this? Scientists need to check that other people’s work is correct. A review process helps ensure conclusions are valid (correct). To be valid, a conclusion must be based on good, logical interpretations of well planned experiments and reliable data. “You haven’t confirmed the Superstring Theory, Blumendraft – this is a whisker from your beard”

How does a scientific theory develop? As evidence from many investigations or experiments done by many different scientists builds up, a hypothesis that has been found true many, many times may become so well supported that scientists consider it a theory

How does a scientific theory develop? Theory: a well-tested explanation that unifies (ties together) many different observations or experiments

Scientific Theory vs. Common Use Theory Important difference: in everyday life, sometimes theory means a guess (e.g. I think that girl likes me) in science, an idea is tested many, many times and proves itself true over & over before it is called a theory (e.g. I asked her to the prom, she said yes; I asked her to marry me, she said yes; we’ve been married 72 years. There is a lot of evidence that she likes me)

Science is an ongoing process that involves: asking questions collecting observing making inferences testing hypotheses

Scientific understanding is always changing. Good scientists are skeptics who question both existing ideas and new hypotheses.

Science and Human Values Decisions involve many factors besides scientific information, including: the society in which we live economic considerations laws moral principles Citizens decide what to do when they vote.