Models in Science

Models in Science What makes a “good” model?

We use to think… • The Earth was the center of the universe • Ptolemeic Model; 100 AD

Now we know… • The Sun is the center of the universe • Copernican Model; 1543 AD

We use to think • The world was flat

Now we know… • The Earth is round • Gallileo (~1600’s) • Christopher Columbus and the New world…

We use to think… • Pluto was our 9th planet

Now… • Pluto isn’t even classified as a planet. • It is a sub-planet (~2007)!

So what makes a “good” model?Let’s Play… • Spend 10 minutes playing with your toy • DO NOT try to explain anything, your job is just to notice stuff. • Make sure everyone gets a turn to play

What are we trying to FIGURE OUT? p12 • Let’s develop a driving question: • A good driving question should be testable… DQ: The fish _________ because_______ and we can test this by ______________

How will we answer our question? • We’ll develop a model • What is a model? • It is a set of ideas about how something in the world works • It is the unseen mechanism that can be used to explain a phenomenon p12

Making a model … • State your driving question • Develop a “test” for one of the variables Group A: wet heat (sweat) – use a cup of hot water Group B: static electricity – use balloons Group C: electric current – use a 9V battery Group D: dry heat – use friction or different body parts Group E: size of your hand Group F: direction the fish points in your hand Group G: temperature – heat your hand or the outside of a dry glass of water (start cold and then raise the temp of the water) • Explain how your variable causes a predictable and repeatable change

Let’s collect some data… p12 • Now, let’s be more systematic and collect some data on our fish • Class Observations: • Group A: • Group B: • Group C: • Group D: • Group E: • Group F: Listen politely to each group presenting their ideas You may ask a question if you raise your hand

Share out with the class… p12 • Figure out a way to keep track of the things you are noticing about the fish • Come up with a PATTERN • Explain what you think is going on with the fish. Use evidence from your observations to support your ideas • Share out with the class. Compare their ideas to yours. How are they similar or different?

How do we choose which one is “right” when there is more than one model? • Which one is the best???

What do I mean by “good”? • In order for a model to be kept and accepted by most people, it has to have the following 4 aspects…..

In summary, a model needs this: • Simplicity • Consistency • Plausibility • Predictability p12

1. Simplicity • A model should be simple. • It should be easy to understand and not too involved. • If it is too complicated, than it may not be the best model out there. Write the letter “s” next to each idea you think is simple

2. Consistency • The model must be consistent with the observations/data available. • If the model doesn’t explain what was seen, than it doesn’t work and should be revised. Write the letter “c” next to each idea you think is consistent

3. Plausibility • The model should be realistic. • If you say there is a gnome named LeRoy that spits on the fish to make it curl up, you lack plausibility. • Your model should build upon/match what you know already. Write the letter “p” next to each idea you think is plausible

4. Predictability • You should be able to predict what will happen if you do a certain thing to the fish…. • Your prediction should come true. • If your prediction is wrong, you need to revise your model. Write the letter “p” next to each idea you think is predictable

p12 Which model(s) were the best? How do you know? Read the article and answer questions 1-6

Models in Science