Variation and Survival

Life Science
Evolution in Living Systems

Individual organisms with certain traits in particular environments are more likely than others to survive and have offspring.

Benchmark: Fossil Record of Life Forms

Explain how the fossil record documents the appearance, diversification and extinction of many life forms.

Benchmark: Anatomy Comparisons

Use internal and external anatomical structures to compare and infer relationships between living organisms as well as those in the fossil record.

Benchmark: Variation & Survival

Recognize that variation exists in every population and describe how a variation can help or hinder an organism's ability to survive.

Benchmark: Adaptations & Extinction

Recognize that extinction is a common event and it can occur when the environment changes and a population's ability to adapt is insufficient to allow its survival.


Standard in Lay Terms 

The environmental conditions influence which organisms will survive and pass on their genes.

Big Ideas and Essential Understandings 

Big Idea:.

The success of an organism, in a changing environment, is affected by the inheritance of characteristics that may give a reproductive advantage.  Extinctions have occurred throughout the history of life and continue to occur. Most species living today did not exist when life first began on Earth. Fossils can be used to study the anatomical features of extinct species.Scientists have found similarities and differences between existing and extinct species which infer biological relationships.

Benchmark Cluster 

MN Standard Benchmarks 

Explain how the fossil record documents the appearance, diversification and extinction of many life forms.

Use internal and external anatomical structures to compare and infer relationships between living organisms as well as those in the fossil record.

Recognize that variation exists in every population and describe how a variation can help or hinder an organism's ability to survive.

Recognize that extinction is a common event and it can occur when the environment changes and a population's ability to adapt is insufficient to allow its survival.


©Gary Larson


Life Science

Content Standard C
As a result of their activities in grade 7, all students should develop understanding of


1.    Structure and function in living systems

2.    Reproduction and heredity

3.    Regulation and behavior

4.    Populations and ecosystems

5.    Diversity and adaptations of organisms

5. The Living Environment: F

During middle school, several lines of evidence are further developed. The fossil evidence can be expanded beyond extinctions and survivals to the notion of evolutionary history. Sedimentation of rock can be brought in to show relative age. However, actual age, which requires an understanding of isotopic dating techniques, should wait until high school, when students learn about the structure of atoms. Breeding experiments can illustrate the heritability of traits and the effects of selection. It was familiarity with selective breeding that stimulated Darwin's thinking that differences between successive generations can naturally accumulate.

By the end of the 8th grade, students should know that

  • Small differences between parents and offspring can accumulate (through selective breeding) in successive generations so that descendants are very different from their ancestors. 5F/M1
  • Individual organisms with certain traits are more likely than others to survive and have offspring. 5F/M2a
  • Changes in environmental conditions can affect the survival of individual organisms and entire species. 5F/M2b
  • Many thousands of layers of sedimentary rock provide evidence for the long history of the earth and for the long history of changing life forms whose remains are found in the rocks. 5F/M3a
  • More recently deposited rock layers are more likely to contain fossils resembling existing species. 5F/M3b
  • Most species that have lived on the earth are now extinct. Extinction of species occurs when the environment changes and the individual organisms of that species do not have the traits necessary to survive and reproduce in the changed environment. 5F/M4** (NSES)
  • Reproduction is necessary for the survival of any species. 5F/M5*

8. The Designed World A Agriculture

  • People control some characteristics of plants and animals they raise by selective breeding and by preserving varieties of seeds (old and new) to use if growing conditions change. 8A/M2*
  • NAEP (optional)

Framework for K-12 Science Education

Fossils are mineral  replacements, preserved remains,  or traces of organisms  that lived in the past. Thousands of layers of sedimentary  rock not only provide  evidence of the history  of Earth  itself but also of changes in organisms whose fossil remains  have been found in those layers. The collection of fossils and their placement  in chronological order (e.g., through the location  of the sedimentary layers in which they are found or through radioactive dating) is known as the fossil record.  It documents the existence, diversity, extinction, and change of many life forms throughout the history  of life on Earth. Because of the conditions necessary for their preservation,  not all types of organisms  that existed in the past have left fossils that can be retrieved. Anatomical similarities and differences between various organisms  living today  and between them and organisms  in the fossil record enable the reconstruction of evolutionary history  and the inference of lines of evolutionary descent. Comparison of the embryological  development of different species also reveals similarities that show relationships not evident in the fully formed anatomy8LS4.A

Genetic variations among  individuals  in a population give some individuals  an advantage in surviving and reproducing in their environment. This is known  as natural selection. It leads to the predominance of certain  traits in a population and the suppression of others.  In artificial selection, humans  have the capacity  to influence certain  characteristics of organisms  by selective breeding. One can choose desired parental traits  determined by genes, which are then passed on to offspring8LS4.B

Common Core Standards (i.e. connections with Math, Social Studies or Language Arts Standards):  Social studies connects with time lines in history.


Student Misconceptions 
  •, Species that have no apparent or obvious similarities have no similarities at all.
  • Extinctions are rare and humans have caused the majority of extinctions.
  •, Most species that lived in the past are still alive today.
  • Except for a few major changes due to large volcanic eruptions or meteorites that have struck the earth, environmental conditions have stayed the same throughout the history of the earth
  • Species that have no apparent, obvious, or superficial similarities have no similarities at all (Shtulman, A. (2006). Qualitative differences between na ̈ıve and scientific theories of evolution. Cognitive Psychology, 52, 170-194).
  • All individuals within a population of organisms are the same. Differences among them are trivial and unimportant. All members of a population are nearly identical 

(Greene, E. D. (1990). The logic of university students' misunderstanding of natural selection. Journal of Research in Science Teaching, 27(9), 875 - 885;  Passmore, C., & Stewart, J. (2002). A modeling approach to teaching evolutionary biology in high schools. Journal of Research in Science Teaching, 39, 185-204;   Anderson, D.L., Fisher, K.M., & Norman, G.J. (2002). Development and evaluation of the conceptual inventory of natural selection. Journal of Research in Science Teaching, 39(10), 952-978;   Shtulman, A. (2006). Qualitative differences between naıve and scientific theories of evolution. Cognitive Psychology, 52, 170-194).


Ms. H pointed to projection screen. "What do you recognize in this image?"


"Lots of bones!"

"A hand!"

"A wrist and arm!"

"It's an xray!"

Ms. H calmed the excitement down, "You are all correct. But what organism's arm and hand does this show?"

"It's mine," answered Davey. "Last year when I broke my arm skateboarding, that is what it looked like. The doctor showed me, the bones and all! Except this hand does not have any broken bones in it."

"You're correct Davey. This is not your hand, though. It is the hand of a chimpanzee."

"But, it looks just like mine," Davey countered.

Sal broke in, "Maybe you're a chimpanzee!"

"Enough, enough. Davey is no chimpanzee."

"Thanks, Ms H," he sighed with relief.

"No, Davey you are no chimpanzee, but what do you have in common with one?"

"The bones in my hand sure looked like those. 'Cept for the broken parts.

This lesson  would be part of  a series of lessons where student get to analyze the data providing evidence for evolution. The comparison of homologous structures in various animals is an easy thing to see and do. If you have skeletons of mammals, birds, reptiles and amphibians available, those provide excellent models. This is a technology based model: it uses xrays of various animals and some easy to use open source software (ImageJ) to manipulate digital images of the forelimbs. The activity calls upon students to differentiate and identify species, but also compare similarities and differences of homology and function.

Each student is directed to a computer station. The handout directs them to open up the images. The students have access to the controls of the software to change the contrast, brightness, colors and a range of tools. The various tools allow structures to stand out, whether they are bone or soft tissue.

The students work through a variety of animals, some familiar (human, other primates) looking and some not so easily identified (lions, bears, owls, whales....).

As they gather data from their observations, they collect it on a table.

Ms. H asks students to pause for a second and step away from the monitor. "What are the differences in some of the bones that you can see?"

"There are some really skinny ones and some really fat ones," says Tina

"They all have the same shape and pattern, at least the five that we've looked at so far,"added James.

"I think I see claws on some, but not all."

"Remember, part of your task is to not only compare structures, but also try and figure out the organism from the list. Then take it a step further to identify the function of the 'animal hand'", said Ms. H.

As the students work through the images and collect data while manipulating the images, information piles up. They find that structures are similar, but the functions may not be. If students have had some training in classifcations and cladistics, a simple cladogram can be created showing the common ancestory. This activity can also be tied to the evolution of whales, where there is lots of fossil evidence showing intermediates along an evolutionary trail. The PBS series "Evolution" has a few minutes of whale evolution that could be used as an extention of this activity along with relating it to current organisms and evolutionary origins. These homologous structures have an evolutionary common ancestory. This activity could be tied together with some biomolecular evidence that shows the number of similar amino acids between these organisms. G/T students would be able to go beyond the visible structural similarities and differences to the level of how are the proteins show relationships From the amino acid similarities, a cladogram could be constructed, showing the evolutionary relationships.


Instructional Notes 

Instructional suggestions/options:

Students need to be actively engaged in examining the nature of science and the various evidence that supports evolutionary biology. Educators have access to many primary sources of data that students can examine: whether they are fossils, model hominid skulls or molecular comparisons.

Selected activities:

  • Stories from the Fossil Record This web-based module provides students with a basic understanding of how fossils can be used to interpret the past. This activity comes from the UC Museum of Paleontology.
  • Interactive Investigation: The Arthropod Story This interactive investigation delves into the amazing world of the arthropods and examines their success and their evolutionary constraints. This activity comes from the UC Museum of Paleontology
  • Solving the Puzzle Darwin formulated his theory of evolution by observing nature and analyzing evidence-or using the scientific process. In this activity, student teams use evidence (jigsaw puzzle pieces) revealed over time to experience the nature of science and understand its limitations.
  • What did T. Rex Taste Like? In this web-based module students are introduced to cladistics, which organizes living things by common ancestry and evolutionary relationships.
  • Adventures at Dry Creek: In this interactive web-based module students conduct a simulated field study at a fossil dig in Montana.
  • Similarities and Differences: Understanding homology and analogy This interactive investigation explains what homologies and analogies are, how to recognize them, and how they evolve.
  • Lines of evidence: The science of evolution The theory of evolution is broadly accepted by scientists - and for good reason! Learn about the diverse and numerous lines of evidence that support the theory of evolution.
  • Big Beans, Little Beans Students measure and note the variation in the lengths of lima beans. Students then compare the growth rate of different sized beans.
  • Clipbirds Students learn about variation, reproductive isolation, natural selection, and adaptation through this version of the bird beak activity.
  • Interpreting Tracks: Students discover the relationships among foot length, leg length, stride length and speed in bipedal animals that provide clues about dinosaur speed.
Instructional Resources 

Additional resources or links

Understanding Evolution This site is jam-packed with information, background and activities for science teachers. From the University of California's Museum of Paleontology

Evolution and the Nature of Science Institutes The main objective of ENSI is to improve the teaching of evolution in science courses by encouraging teachers to teach evolutionary thinking in the context of a more complete understanding of modern scientific thinking. This resource is loaded with student engaging activities that address the nature of science through direct experiencs.

Virus and the Whale: Exploring Evolution in Creatures Small and Large Judy Diamond, Editor with Carl Zimmer, E. Margaret Evens, Linda Allison, and Sarah Disbrow What middle schooler could resist an invitation to follow seven scientists to their labs and into the field, going inside the body to meet a virus, underground to meet leaf-cutter ants, to the deserts of Pakistan to say hello to skeletons of ancient whales ... and more. NSTA Press Arlington, VA 2006 ISBN: 9780873552639

The Magic Hooey Stick Science deals only with natural patterns and mechanisms. Understanding science enables one to differentiate it from pseudoscience, superstition, and non science. This activity addresses the difference between science and non-science, a great way to start the concept of evolution.

Minnesota Citizens for Science Education This organization is working to assure the teaching and learning of evolutionary biology and other sciences in Minnesota's K-12 public school classrooms. The organization has many resources for Minnesota science educators.

New Vocabulary 


  • fossil  preserved remains of of ancient organisms
  • sedimentary rock is a type of rock that is formed by sedimentation of material at the earth's surface and within bodies of water.
  • fossil record was one of the early sources of data relevant to the study of evolution.
  • adaptation  heritable characteristic that increases an organisms ability to survive and reproduce in an environment
  • homologous structure  structures that are similar in different species of common ancestry
  • natural selection  process by which organisms that are most suited to their environment survive and reproduce most successfully.
  • extinction  No longer existing or living
  • variation  Something slightly different from another of the same type
  • population  All the organisms that constitute a specific group or occur in a specified habitat
  • traits   A genetically determined characteristic or condition
  • diversity  Variety or multiformity
Technology Connections 

Internet connections if possible. Being connected to the web offers a link to places all across the planet. Students may be able to view a fossil dig in real time, converse with scientists via Skype or Facetime, connect with classes in other parts of Minnesota, the United States or the world.

Computers with access to images and image processing software (ImageJ for example). The image bases of the web hold incredible promise to add evidence that support and explain the process of evolution.

Cameras in the classroom and on phones allow students to present data to one another in creative and real time ways.

Cross Curricular Connections 

Math skills are used in determining the years on time lines.



Which of the following have scientists found when they have compared and contrasted an existing species?

1.    They have found similarities and they have found differences.

2.    They have found similarities, but they have not found differences.

3.    They have found differences, but they have not found similarities.

4.    There is no way to compare extinct and existing species.

What is TRUE about environmental conditions on earth?

1.    Environmental conditions on earth have always been the same, except for minor changes from year to year.

2.    Environmental conditions on earth changed in the past, but they are not changing now.

3.    Environmental conditions on earth stayed the same in the past, but they are changing now.

4.    Environmental conditions on earth changed in the past, and they are changing now.

Fossils can be used for which of the following?

1.    To study the anatomical features of extinct species and to compare the features of the extinct species with those of existing species.

2.    To study the anatomical features of extinct species, but not to compare the features of extinct species with those of existing species.

3.    To compare the features of extinct species with those of existing species, but not to study the anatomical features of extinct species.

4.    Neither to compare the features of extinct species with those of existing species nor to study the anatomical feature of extinct species.


  • How can evolution be scientific when no one was there to see it happen?
  • Are we keeping our biases out of our teaching of evolution?
  • Can all of student's questions be answered responsibly?
  • What define a good theory? With any theory one can predict forward and predict backwards  as well.   What can fossils tells us?  What is our future?


  • Students making phylogenetic trees.
  • Students studying change over time by looking at fossils.
  • Students studying various bones to compare as in the vignette.


Struggling Learners 

Struggling and At-Risk:

Snow, D. (2003). Noteworthy perspectives: Classroom strategies for helping at-risk students (rev. ed.). Aurora, CO: Mid-continent Research for Education and Learning.

In 2002, McREL conducted a synthesis of recent research on instructional strategies to assist students who are low achieving or at risk of failure. From this synthesis of research, McREL identified six general classroom strategies that research indicates are particularly effective in helping struggling students achieve success.

Hands on activities as in the vignette will help at risk students.

A picture time line may be at some at risk student's ability.

If possible visit a site that contains fossils and have students collect and examine various fossils

English Language Learners 

Herr, N. (2007). The sourcebook for teaching science. This page contains                strategies to help teachers better attend to the needs of their ELL learners. These strategies are grouped according to the following learning tasks:                            listening, visualization, interpersonal communication, laboratory,                               demonstrations, reading and writing, instruction and vocabulary

Posters will also allow ELL students to use pictures to help with the vocabulary necessary

Extending the Learning 


Teachers First is an educational support website that may help with G/T students

Cogito is another website that is available for G/T Students.


Science education should include the use of culturally relevant content.  Atwater (1995a-c) and Banks(1987,1988) have proposed several ways to integrate culturally relevant content into the curriculum.  The value of using such approaches is that they can improve the conversation about beliefs in science and hone beliefs about science for all students.

Posters will also allow multi-cultural students to use pictures to help with the vocabulary necessary.

Multicultural science education.  Official NSTA Position Statement.

Freelang.net hosts a English to Ojibwe and Ojibwe to English dictionary that may be used to look up meanings to vocabulary words.

Activities like those in the vignette would help students.

Special Education 

Technologies for Special Needs Students: In their newsletter, "Tech Trek",  from the National Science Teachers Association, there are suggestions for using technology including voice recognition software

Hands on labs like the one in the vignette helps special ed students comprehend concepts better than straight book work.


  • Parents may hear about x-rays of different  organisms looking similar (vignette)
  • Parents may see time lines coming home.
  • Parents may hear about fossil hunting.