Evolution Through Natural Selection: A Critical Thinking

Tool

Daniel LoxtonSkepticism in the Classroom

The Amazing Meeting 8

Using Evolution to Teach Critical Thinking Skills

Discussing ScienceThree Topics for Critical ThinkingAssessing LearningAdditional Resources

Using Evolution to Teach Critical Thinking Skills

Discussing Science

◦What is science?

◦Canons of science?

◦The language of science

Discussing Science

Science is how we learn about the world which assumes that the best way to learn what is true is using:

◦ Empirical evidence (what we observe) All of the flowers planted in the sun grew.

None of the flowers planted in the shade grew.

◦ Logic (connecting two or more observations to draw a new conclusion) Flowers need the sun in order to grow.

Discussing Science - Canons

Determinism: We assume that everything that happens has a natural explanation.

Empiricism: Genuine knowledge is deduced from observations. If we cannot deduce it from observations, we cannot test it.

Testability: If we cannot falsify it, we cannot test it.

Parsimony/Simplicity: Occam’s Razor tells us that, given more than one explanation and all other things being equal, the simplest explanation is the mostly likely to be correct.

Discussing Science - Language

Law: a simple statement about the way something works◦ Any floating object displaces its own weight of fluid. –

Archimedes Principle◦ For every action there is an equal and opposite reaction. -

Newton’s 3rd Law of Motion Hypothesis: a simple statement about the way something

works which is not supported by evidence (yet)◦ Chewing gum while talking a test results in higher scores than not

chewing gum. Theory: explains or predicts a number of things that we can

observe

Using Evolution to Teach Critical Thinking Skills

Discussing ScienceThree Topics for Critical Thinking◦ If evolution is about the best features surviving, why

isn’t all life evolving the same way?

◦Will we stop evolving when we are perfect?

◦How did birds get wings?

Why are there different species?

If evolution is about survival of the fittest, why isn’t all life evolving the same way?

◦ Objectives: Understand the definition of “fit”

Understand how environmental pressures favor some features over others

Understand how creatures compete for limited resources

Understand how species adapt to compensate or compromise

Why are there different species?

For example, a shorter species of tree must either adapt to grow taller or to require less sunlight.

There is a limited supply of water, food, and space. Competition for these resources requires us to either adapt or die.

Why are there different species?

The web of life is complex because survival requires each species to work with what is available. ◦ Animals eat seeds and carry them to new locations

◦ Bees carry pollen from flower to flower; in return, flowers produce nectar which bees eat.

◦ Earthworms break down dead plants by chewing and digestion. They also bore holes which let oxygen in, moving decomposition along.

Will we stop when we are perfect?

If evolution is about survival of the fittest, why isn’t all life evolving the same way?

◦ Objectives: Understand the definition of “fit”

Understand the trade-offs required for many adaptations

Understand how environmental pressures shape variables by favoring some values over others

Survival of the Fittest

If evolution is about the best features surviving, why isn’t all life evolving the same way?

◦How long should a bird’s tail be?

◦What color is best for [animal or plant]?

◦What is the best [eye, number of limbs, height, or any other feature]?

What color is best for… a moth?

Ask children this question and they will likely tell you what color a moth is.

Encourage them to think about why a moth is the color that it is.

The story of the peppered moth is an excellent example of natural section.

Survival of the fittest

How long should a bird’s tail be?

How long should a bird’s tail be?

How long should a bird’s tail be?

A peacock’s tail is attractive to mates, but it is not well-suited for flight.

Photo by: www.tribuneindia.com

Features usually require trade-offs

Mechanisms For Change

How did birds get wings?

◦ Objectives: Understand the definition of “fit”

Understand how environmental pressures favor some features over others

Envision how features can develop slowly

How did birds get their wings?

Developing hypotheses, they are likely to guess:◦ A generation was born with them ◦ They grew on living birds◦ An intelligent agent designed them◦ Natural selection

Choosing the best explanation◦ Do any require an unreasonable (e.g., supernatural)

assumption?◦ Which is the simplest?◦ Which explains the most data (observations)?

How did birds get their wings?

Evaluate their explanationsWhich is the simplest?Which explains the most data?◦ To answer these, ask these:

What are the advantages?

Did they appear suddenly or gradually?

How?

How did birds get their wings?

What are the advantages?Did they appear suddenly or gradually?How?

Using Evolution to Teach Critical Thinking Skills

Discussing ScienceThree Questions for Critical ThinkingAssessing Learning◦ Emphasize understanding

◦Assess understanding

◦Use assessments effectively

Assessing Learning

Emphasize understanding, not memorization◦ The best way to motivate someone to learn is to provide

consequences for learning.

Assess understanding, not memorization◦ NO MULTIPLE CHOICE – these do not assess learning,

encourage memorization strategies, and create false memories.

◦ The assessment dictates how people prepare.

Objectives should be broad and basic.

Short answer and essay are the best means of assessing understanding.

Assessing Learning

Use assessments effectively◦Again, the assessment dictates what people will do

to prepare for it because they rely on grades.

◦Use assessments to understand how your students are studying.

◦Use assessments as another opportunity to present material for the course to students.

◦ If it is a college course, provide a cumulative assessment.

Using Evolution to Teach Critical Thinking Skills

Discussing ScienceThree Questions for Critical ThinkingAssessing LearningAdditional Resources◦ Evolution: How We and All Living Things Came

to Be by Daniel Loxton provided most of the examples suggested here.

◦ The internet is a great source of information, but choose wisely

Additional Resources

No Answers in Genesis: http://www.noanswersingenesis.org.au/teaching_evolution.htm

Understanding Evolution: http://evolution.berkeley.edu/

PBS on Evolution: http://www.pbs.org/wgbh/evolution/change/deeptime/index.html

Swarthmore College: Evolution resources for the public school teacher http://www.swarthmore.edu/NatSci/cpurrin1/evolk12/teaching/resources.htm

National Center for Science Education [NCSE]http://ncse.com/evolution/education/links-teachers