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Evolution ExplorationsEvolution-Explorations

  • Subject:
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  • Grade(s): 6-8
  • |
  • Duration: Two class periods

Lesson Plan Sections

Objectives


Students will understand the following:
1. Humans have behavioral traits and characteristics in common with other animals.
2. These shared traits may be considered evidence in favor of the claim that humans and all animals have evolved from a common early ancestor (a single cell).

Materials


For this lesson, you will need:
• Animals to observe in class, at home, or at a zoo or farm

Procedures


1. Begin the activity with a discussion about pets that your students own or know. Do the pets sometimes do things that seem human? Are any of the pets treated by their owners as members of the family? In what ways?
2. Tell the class that they will be observing animals in order to compare their behavioral traits and characteristics with those of human beings.
3. Divide the class into groups, making sure, if possible, that at least one member of each group has a pet or a friend's pet to observe. If no pets are available, arrange for students to visit a zoo or farm, or a place where they can observe familiar wild animals outdoors.
4. Ask each group to spend at least one hour observing the animal it has chosen. As group members observe, they should take notes on the animal's physical appearance and behavior, focusing on any behaviors that strike them as being similar to human behaviors.
5. When their observations are complete, students should write a few paragraphs describing what they saw and comparing their animal's behaviors to human behaviors.
6. Allow time for students to share what they have written.
7. Lead a discussion about the implications of students' observations. Should the similarities between human behaviors and the behaviors of other animals be considered evidence in favor of the claim that all animals, including humans, descended from a common ancestor (a single cell)? Encourage arguments both for and against the claim.

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Adaptations


Adaptations for Older Students:
Have students do research on the Internet to find out what scientists have to say about the claim that all animals descended from a common single-cell ancestor. What scientific evidence do we have for or against that claim?

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Discussion Questions


1. How much of your brain's activity involves conscious thought (e.g., thinking about what your brain is doing)? How much of your brain's activity do you not even think about? Consider what your brain is doing right now: What tasks is it doing that you don't have to "ask" it to do? What tasks is your brain doing only because you've "asked" it to?
2. Most types of cells in our bodies regenerate (die and then grow anew). Heart cells and nerve cells, however, do not. Why do you think that most of our cells regenerate? Why don't we keep the same cells for our entire life? What would be the advantages and/or disadvantages of having our heart and nerve cells regenerate?
3. The theory of evolution states that, over hundreds of millions of years, simple early life forms such as bacteria changed and developed into more complex life forms, eventually leading to the development of human beings. Discuss how this process works and how life forms can change over generations.
4. Based on your knowledge of and experience with animals, what evidence do you have of a common ancestor for all animals? What do humans have in common with all other animals? Which animals are we most closely related to and why? Can you think of things we have in common with animals that seem very different from us, such as cats, dogs, birds, and insects?
5. Discuss the ways in which our bodies and minds change as we get older. How do animals change as they get older?
6. Why is it important to understand not only the science behind the human body, but also the emotions and personalities that everyone possesses?

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Evaluation


You can evaluate your students on their written work using the following three-point rubric:
  • Three points: descriptions of animal's behavioral traits clear and vivid; comparison with human behaviors convincing and supported with examples

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  • Two points: clear descriptions of animal's behavioral traits; comparisons with human behaviors lacking examples

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  • One point: descriptions of animal's behavioral traits vague; comparisons unconvincing

You can ask your students to contribute to the assessment rubric by determining criteria for clear and vivid descriptions of animal behavior.

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Extensions


Time Travel
Divide the class into small groups, and then ask the members of each group to imagine that they can travel back in time. Tell them that they will travel back to the time periods 3 billion, 550 million, 80 million, 1 million, and 30,000 years ago. Assign each group one of those time periods; then have students research the history of Earth and of evolution, either in the library or on the Internet, to find out what life-forms existed during their time period. (A recommended Internet resource is the University of California Museum of Paleontology time machine atucmp.berkeley.edu.) Have groups create an illustration—a poster, perhaps, or a painting—of the various life-forms students would see on their time journeys. They should include written captions that describe what they have drawn.

Bodily Functions
Ask your students to make a guess about the number of times throughout their lives that they will do the following things: laugh, cry, exercise, eat (meals and snacks), urinate, defecate, breathe, and blink. Then ask them to estimate the amount of time throughout their lives that they will spend asleep. After they've made and recorded their guesses, have them spend one week recording precisely the number of times they perform each of those functions. (They can simply count the number of times they breathe and blink in a minute, and then multiply by the appropriate number.) At the end of the week, have students calculate how many times they will perform each function in their lifetimes if they live out their full life expectancies (about 79 years for women and 72 for men in the United States). Then invite students to participate in a discussion contrasting the amount of time humans spend performing simple functional or survival activities with the amounts of time spent on such activities by other animals and by earlier humans. Discuss what their contrasts imply about the differences between humans and other animals or earlier ancestors.

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Suggested Readings


The Human Body Explained
Edited by Philip Whitfield. Henry Holt & Co., 1995.
This lavishly illustrated introduction to the functions of the human body contains clearly written text that uses comparisons and analogies from everyday life to convey the facts about our "incredible living machine." The book also features brilliant color photos, diagrams, and sidebars that make understanding these complex concepts a breeze.

Incredible Voyage: Exploring the Human Body
Edited by Toni Eugene and Tom Melham. National Geographic Society, 1998.
A vivid, highly readable portrait of human physiology as we understand it on the brink of the 21st century. Six chapters, highlighted by 300 colorful, state-of-the-art illustrations, trace the development, structure, and function of the human organism from conception to old age.

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Links


AMA Health Insight: The Atlas of the Human Body
Shows the basic anatomy and function of the body's organ systems.

Exploratorium: Which Embryo is Human?
This site shows the amazing similarity between embryos of fish, chickens, dogs, lizards, and humans.

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Vocabulary


Click on any of the vocabulary words below to hear them pronounced and used in a sentence.
speaker    bile
Definition: A yellowish or greenish fluid secreted by the liver, which aids in the digestive process.
Context: Bile is released into the small intestine during the digestion process.
speaker    cochlea
Definition: A division of the labyrinth of the ear.
Context: The bones of the inner ear transfer the vibrations of the eardrum to receptors in the cochlea.
speaker    evolution
Definition: The theory that the various types of animals and plants have their origin in other preexisting types, the distinguishable differences being due to modifications in successive generations.
Context: Changes in the environment three billion years ago caused the process of evolution to begin, gradually allowing bacteria species to adapt and develop into more complicated species.
speaker    hydrochloric acid
Definition: A strong, corrosive, irritating liquid acid that is normally present in dilute form in gastric juice.
Context: The stomach contains enzymes and hydrochloric acid, which allow it to digest food.
speaker    magnetic resonance
Definition: The response of electrons, atoms, molecules, or nuclei to certain discrete radiation frequencies.
Context: Doctors can use a magnetic resonance scanner to take detailed pictures of the inside of the body.

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Standards


This lesson plan may be used to address the academic standards listed below. These standards are drawn from Content Knowledge: A Compendium of Standards and Benchmarks for K-12 Education: 2nd Edition and have been provided courtesy of theMid-continent Research for Education and Learningin Aurora, Colorado.
 
Grade level: 6-8
Subject area: life science
Standard:
Knows the general structure and functions of cells in organisms.
Benchmarks:
Knows that multicellular organisms have a variety of specialized cells, tissues, organs, and organ systems that perform specialized functions (e.g., digestion, respiration, reproduction, circulation, excretion, movement, control and coordination, protection from disease).

Grade level: 6-8
Subject area: life science
Standard:
Understands the nature of scientific inquiry.
Benchmarks:
Knows possible outcomes of scientific investigations (e.g., some may result in new ideas and phenomena for study; some may generate new methods or procedures for an investigation; some may result in the development of new technologies to improve the collection of data; some may lead to new investigations).

Grade level: 6-8
Subject area: life science
Standard:
Understands the genetic basis for the transfer of biological characteristics from one generation to the next.
Benchmarks:
Knows that the characteristics of an organism can be described in terms of a combination of traits; some traits are inherited and others result from interactions with the environment.

Grade level: 6-8, 9-12
Subject area: life science
Standard:
Knows about the diversity and unity that characterize life.
Benchmarks:
Benchmark 6-8:
Knows evidence that supports the idea that there is unity among organisms despite the fact that some species look very different (e.g., similarity of internal structures in different organisms, similarity of chemical processes in different organisms, evidence of common ancestry).

Benchmark 9-12:
Knows how organisms are classified into a hierarchy of groups and subgroups based on similarities that reflect their evolutionary relationships (e.g., shared derived characteristics inherited from a common ancestor; degree of kinship estimated from the similarity of DNA sequences).

Grade level: 6-8, 9-12
Subject area: life science
Standard:
Understands the basic concepts of the evolution of species.
Benchmarks:
Benchmark 6-8:
Knows basic ideas related to biological evolution (e.g., diversity of species is developed through gradual processes over many generations; biological adaptations—such as changes in structure, behavior, or physiology—allow some species to enhance their reproductive success and survival in a particular environment).

Benchmark 9-12:
Knows that natural selection leads to organisms that are well suited for survival in particular environments, so that when an environment changes, some inherited characteristics become more or less advantageous or neutral, and chance alone can result in characteristics having no survival or reproductive value.

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Credit


Betsy Hedberg, former middle school teacher, current freelance curriculum writer and consultant.

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