Scientific Method

Science is a process we use to gain knowledge and make discoveries What is science? Making observations and carrying out experiments to learn how things happen Science is a process we use to gain knowledge and make discoveries

To satisfy our curiosity and understand the world around us Why do we do it? To satisfy our curiosity and understand the world around us To solve problems

Scientific Method Observe and State a Problem Form a Hypothesis Test the Hypothesis Record and Analyze Data Form a Conclusion Repeat the Experiment

Curiosity and Interest Observe a Problem Curiosity and Interest Must be answerable by science Word your question appropriately State a Problem Humans are naturally curious – check out a 3-year old exploring their surroundings and asking questions Adults aren’t much different than children in this respect We have lots of questions and I encourage you to ask yours without reserve. Any questions you have are probably common to many in the room Some questions are not answerable by science – “Why am I here?” involves faith and some reason behind our existence The question can be reworded to “How did I get here”, which can be answered by science and has been – evolution has been thoroughly studied… Another example – “which came first the chicken or the egg?” vs. “which came first, the chicken egg or the chicken?”

Observe and State a Problem We all see leaves change color in autumn. Where do all those beautiful reds and yellows come from? Problem: How do leaves change color in autumn? Problem: How do Maple leaves change color in autumn? X How do leaves change color is too broad…there are many different types of trees that change color. How can we fix this? Make it more specific and choose 1 tree.

Scientific Method Observe and State a Problem Form a Hypothesis Test the Hypothesis Record and Analyze Data Form a Conclusion Repeat the Experiment

What is a hypothesis An educated guess! Think of some possible explanation for the stated problem Can be wrong or right Must be testable Whether or not your hypothesis is correct is not the most important thing. You will use the rest of the scientific method to test and validate your hypothesis. The most important thing is the conclusion you make at the end of your process. Testable – “our universe is surrounded by another, larger universe, with which we have absolutely no contact” Rejectable – “there are other inhabited planets in the universe” vs. “any two objects dropped from the same height above earth will hit the ground at the same time, as long as air resistance is not a factor” For example – the gravity hypothesis…you’d have to show that every single pair of objects hit the ground at the same time…that is impossible This is where the term theory comes in…in science a theory is a well-tested hypothesis that has a lot of evidence in its favor. There is no way to prove some things correct, but there are enough cases where the hypothesis is true, that we think of it as being true (call it a theory – theory of evolution, theory of gravity)

Maple Tree Leaves Possible explanation? Change color in fall…what happens in fall? Temperature changes! Hypothesis: a change in temperature is related to a change in leave color? NO...more specific Hypothesis: A decrease in temperature is related to Maple leaves changing color. Hypothesis: A change in temperature is related to Maple leaves changing color.

Scientific Method Observe and State a Problem Form a Hypothesis Test the Hypothesis Record and Analyze Data Form a Conclusion Repeat the Experiment

Test your Hypothesis Test through observation (evolution) Test through experimentation Provide evidence for or against hypothesis

Test your Hypothesis Controlled experiment Isolate/test a single variable Set up a control group Independent variable Dependent variable Why wouldn’t you want to test more than 1 variable at once and how do you know what that variable should be? The hypothesis sets this up for you. The variable you test is basically the thing you think is responsible for whatever problem you’re testing. You can isolate one variable by setting up 2 parts to the experiment – control and experimental Control – tests the effects of all the other variables; Experimental tests the one variable you picked out. It will be more clear when we see our tree example setup. The control and experimental setup look exactly the same except for our one isolated variable. You won’t know which one actually caused the result you wanted if you have more than 1 thing different. If you set up it up so you’re only testing one variable, you know any differences you see are because of that one variable. This variable is what we are testing. It is called the independent variable. The independent variable is what we’re changing The dependent variable is what we’re observing. This is the variable that should change between the experimental and control setup if the hypothesis is valid. Placebo effect? Remember: A decrease in temperature is related to Maple leaves changing color.

A decrease in temp is related to Maple leaves changing color. What stays the same in both? What varies? What are some variables that stay the same in this experiment? The pot size, tree size, water at same time, identical chambers Temperature

Scientific Method Observe and State a Problem Form a Hypothesis Test the Hypothesis Record and Analyze Data Form a Conclusion Repeat the Experiment

Record observations What are the important indicators in your experiment? Keep careful and frequent notes of observations (your data) What do I mean by indicators? Things that will confirm or deny the hypothesis

Analyze Data Visual aids (graphs and tables) Correlation vs. causation: Ice cream sales and number of drowning deaths are correlated? Does eating ice cream cause you to drown? Causation – X causes Y Red Sox game causes an increase in traffic Common response – X and Y change in response to a 3rd variable (Ice cream and drownings occur in summer)

Maple Tree Leaves Good indicator? Number of leaves that changed color Time the leaves take to change colors

Scientific Method Observe and State a Problem Form a Hypothesis Test the Hypothesis Record and Analyze Data Form a Conclusion Repeat the Experiment

DOES THE DATA SHOW THE HYPOTHESIS TO BE FALSE OR TRUE? Form a Conclusion From your analysis, answer the question: DOES THE DATA SHOW THE HYPOTHESIS TO BE FALSE OR TRUE? If it’s false – may reject the hypothesis as wrong and start all over again with a new hypothesis If it’s true – move on to the next step in the scientific method

Decrease temperature –color changes What data would confirm our hypothesis? What does this data tell us? Confirmation – more leaves change color in the experimental setup with cold air Rejection – Leaves on both or neither trees change color Our data says – very few leaves on both changed color, probably not temperature alone We can come up with alternate hypothesis – day length, wind, rainfall…it may be a combination of these things

Scientific Method Observe and State a Problem Form a Hypothesis Test the Hypothesis Record and Analyze Data Form a Conclusion Repeat the Experiment

Repeat the Experiment Does confirmation of the hypothesis prove it to be true? Need to repeat the experiment many times – show it did not happen by chance Publish in journals for others to try NO!

Observe and State a Problem You arrive home late at night, walk up to your house door, unlock the door, reach in to the light switch just inside the front door. The light does not come on! Now what? Problem: Why isn’t the light working?

Light problem Hypothesis: Experiment: . Data/Analysis: Conclusion: The power is out Check electronics/other houses in area Your alarm clock works Reject hypothesis – power is not out

More testing… Hypothesis: Experiment: Data/ Analysis: Conclusion: Light bulb loose in socket Tighten bulb, flip switch Does not turn on Reject hypothesis – bulb being loose is not the problem

Repeat process Hypothesis: Experiment: Data/Analysis: Conclusion: . Light bulb burned out Install a new bulb New bulb works! Can’t reject hypothesis, but can’t confirm it either Shake old bulb…tinkle? YES! There is tinkling! Confirm hypothesis! Bulb was burned out

Questions? Observe and State a Problem Form a Hypothesis Test the Hypothesis Record and Analyze Data Form a Conclusion Repeat the Experiment