This unit builds toward these performance expectations:

• HS-LS1-3 Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis.
• HS-LS2-6* Evaluate the claims, evidence, and reasoning that the complex interactions in ecosystems maintain relatively consistent numbers and types of organisms in stable conditions, but changing conditions may result in a new ecosystem.
• HS-LS2-7* Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity.
• HS-LS4-1 Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence.
• HS-LS4-2* Construct an explanation based on evidence that the process of evolution primarily results from four factors: (1) the potential for a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited resources, and (4) the proliferation of those organisms that are better able to survive and reproduce in the environment .
• HS-LS4-4* Construct an explanation based on evidence for how natural selection leads to adaptation of populations.
• HS-LS4-5* Evaluate the evidence supporting claims that changes in environmental conditions may result in: (1) increases in the number of individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other species.
• HS-ESS2-7† Construct an argument based on evidence about the simultaneous coevolution of Earth’s systems and life on Earth.

†This performance expectation is developed across multiple courses.

*This performance expectation is developed across multiple units within this course.

LS1.A. From Molecules to Organisms: Structures and Processes

• Feedback mechanisms maintain a living system’s internal conditions within certain limits and mediate behaviors, allowing it to remain alive and functional even as external conditions change within some range. Feedback mechanisms can encourage (through positive feedback) or discourage (negative feedback) what is going on inside the living system. (HS-LS1-3)

LS2.C. Ecosystem Dynamics, Functioning, and Resilience

• A complex set of interactions within an ecosystem can keep its numbers and types of organisms relatively constant over long periods of time under stable conditions. If a modest biological or physical disturbance to an ecosystem occurs, it may return to its more or less original status (i.e., the ecosystem is resilient), as opposed to becoming a very different ecosystem. Extreme fluctuations in conditions or the size of any population, however, can challenge the functioning of ecosystems in terms of resources and habitat availability. (HS-LS2-2),(HS-LS2-6)
• Moreover, anthropogenic changes (induced by human activity) in the environment— including habitat destruction, pollution, introduction of invasive species, overexploitation, and climate change—can disrupt an ecosystem and threaten the survival of some species. (HS-LS2-7)

LS4.A: Evidence of Common Ancestry and Diversity

• Genetic information, like the fossil record, provides evidence of evolution. DNA sequences vary among species, but there are many overlaps; in fact, the ongoing branching that produces multiple lines of descent can be inferred by comparing the DNA sequences of different organisms. Such information is also derivable from the similarities and differences in amino acid sequences and from anatomical and embryological evidence. (HS-LS4-1)

LS4.C: Adaptation

• Evolution is a consequence of the interaction of four factors: (1) the potential for a species to increase in number, (2) the genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for an environment’s limited supply of the resources that individuals need in order to survive and reproduce, and (4) the ensuing proliferation of those organisms that are better able to survive and reproduce in that environment. (HS-LS4-2)
• Changes in the physical environment, whether naturally occurring or human-induced, have thus contributed to the expansion of some species, the emergence of new distinct species as populations diverge under different conditions, and the decline–and sometimes the extinction–of some species. (HS-LS4-5),(HS-LS4-6)
• Species become extinct because they can no longer survive and reproduce in their altered environment. If members cannot adjust to change that is too fast or drastic, the opportunity for the species’ evolution is lost. (HS-LS4-5)

LS4.D Biodiversity and Human

• LS4.D.1 Biodiversity is increased by the formation of new species (speciation) and decreased by the loss of species (extinction). (secondary to HS-LS2-7)

ESS2.E. Earth’s Systems

• The many dynamic and delicate feedbacks between the biosphere and other Earth systems cause a continual co-evolution of Earth’s surface and the life that exists on it. (HS-ESS2-7)

ETS1.B Developing Possible Solutions

• When evaluating solutions, it is important to take into account a range of constraints, including cost, safety, reliability, and aesthetics, and to consider social, cultural, and environmental impacts. (HS-ETS1-3)

This unit intentionally develops students’ engagement in these practice elements:

• Engaging in Argument from Evidence
  • Evaluate the claims, evidence, and/or reasoning behind currently accepted explanations or solutions to determine the merits of arguments.
  • Construct, use, and/or present an oral and written argument or counter-arguments based on data and evidence. Evaluate competing design solutions based on jointly developed and agreed-upon design criteria.
  • Evaluate competing design solutions to a real-world problem based on scientific ideas and principles, empirical evidence, and/or logical arguments regarding relevant factors (e.g., economic, societal, environmental, and/or ethical considerations).

The following science and engineering practices are also key to the sensemaking in this unit:

• Asking Questions and Defining Problems
• Developing and Using Models
• Obtaining, Evaluating, and Communicating Information

This unit intentionally develops students’ engagement in these crosscutting concept elements:

Patterns

• Different patterns may be observed at each of the scales at which a system is studied and can provide evidence for causality in explanations of phenomena.
• Empirical evidence is needed to identify patterns.

Scale, Proportion, and Quantity

• The significance of a phenomenon is dependent on the scale, proportion, and quantity at which it occurs.
• Some systems can only be studied indirectly as they are too small, too large, too fast, or too slow to observe directly.

The following crosscutting concepts are also key to the sensemaking in this unit:

• Cause and Effect
• Stability and Change

Which elements of NOS are developed in the unit?

• Science is a Way of Knowing. Science is a unique way of knowing and there are other ways of knowing.
• Scientific KnowledgeAssumes an Order and Consistency in Natural Systems. Scientific knowledge is based on the assumption that natural laws operate today as they did in the past and they will continue to do so in the future
• Science is a Human Endeavor. Individuals and teams from many nations and cultures have contributed to science and to advances in engineering.
• Science Addresses Questions About the Natural and Material World. Science knowledge indicates what can happen in natural systems—not what should happen. The latter involves ethics, values, and human decisions about the use of knowledge.

How are they developed?

• In Lesson 1, students are introduced to data from Inuvialuit community members whose observations illustrate the ways they know about the natural world their community is a part of.
• This evidence is used in conjunction with western scientific sources which represent another way of knowing.
• Throughout the unit, students draw on their understanding of evolution by natural selection with the assumption that this mechanism will operate in the future as it has in the past. In addition, they use what they figure out about Earth’s geologic past, to make predictions about the future.
• Arctic research necessitates collaboration between many nations and cultures. The data utilized in this unit is often from a collaboration between members from many different cultures, communities, nations and traditions.
• In Lesson 8, students use their scientific knowledge about what could happen to polar bears in the future to consider what should happen using criteria such as ethical consideration.

In the anchoring phenomenon, students encounter the sighting of 3 bear species in one location in Canada for the first time, which may be related to the effect of climate change. Students investigate why all three bears may be adapted to the habitats in this area. They conduct a data exploration about changes to Arctic ice and tundra due to climate change and investigate how the 3 bear species could be affected by those changes. Students investigate the relationship between changing Arctic sea ice conditions and the stability of polar bear populations using both Traditional Knowledge and Western scientific sources. They develop initial models to predict how changes in Arctic ice conditions due to a warming climate may affect different polar bear populations in the future. They generate questions that they need to answer to be able to fully explain their models. The phenomenon was chosen because it gives students a real-world context to investigate common ancestry, biological evolution, speciation, and extinction and also provides a way to bring together what they figured out in past OpenSciEd units to consider the gravity of the problem and decide what, if anything, should be done to protect species from extinction. Students understand conservation, the effect of climate change on the Arctic, and connections between habitat fragmentation and evolution from previous units. The fate of the polar bear generated high student interest across racial and gender identities in a national survey. 

The bears  phenomenon was chosen from a group of phenomena aligned with the target performance expectations based on the results of a survey administered to students from across the country and in consultation with external advisory panels that include teachers, subject matter experts, and state science administrators. The phenomenon was chosen for the following reasons:

• Students showed high interest in questions related to hybrid bears.
• It provides a diverse suite of entry points for students across the unit to make local, cultural, and/or relevant community connections so that students’ background knowledge and frames of reference are assets for their sensemaking work.
• Teachers and administrators saw the phenomenon as interesting and on grade band.
• Explaining the phenomenon addresses all the DCIs in the bundle at a high school level.

This unit is the fifth and final in the OpenSciEd High School Biology course sequence.

The unit is organized into two lesson sets. Lesson Set 1 (Lessons 1-5) focuses on figuring out how and why the Arctic bears interact in particular ways and how speciation occurred between the bears over geologic time. Lesson Set 2 (Lessons 6-9) helps students begin to unravel the speed at which extinction and speciation events normally occurred compared with changes to bears that live in the modern-day Arctic. They figure out that hybridization is another way forward for Arctic bears and continue to debate what role humans should play in protecting Arctic ecosystems and species in danger of extinction from climate change. This unit culminates with a transfer task where they apply all of their understanding of how to figure out why the bumble bee is threatened with extinction.

This is the last unit of the High School Biology Course in the OpenSciEd Scope and Sequence. Given this placement, several modifications would need to be made if teaching this unit earlier in the year course. The unit intentionally builds on student understanding built throughout the course, including ideas about ecosystems, inheritance, variation of traits, natural selection, and evolution of populations. Additional support would be needed in all of these areas if this unit were taught out of sequence.

To extend or enhance the unit, consider the following:

• Lesson 2: If students have demonstrated proficiency on DCI elements related to cellular respiration, consider modifying this portion of the lesson to condense it.
• Lesson 3: Ask students to search for other bear trees and motivate them to figure out why the trees might be different. What type of data was the tree built with? What algorithm was used to build the tree? Students could explore why different types of DNA (coding sequences, non-coding sequences, or mitochondrial DNA) might create different types of trees.
• Lesson 7: This lesson only briefly touches on the causes and effects of the 5 mass extinction events in Earth’s histories. Students who show high interest may be encouraged to investigate the causes and effects of these events in more detail.  
• Lesson 8: If time allows, let students develop the criteria for their research and develop their own way to organize their notes to record what they figure out.
• Lesson 8: If time and interest allows, students could spend more time researching each case study to better inform the final discussions on day 3.

• Kate Henson, Revision Unit Lead, University of Colorado Boulder
• Douglas Watkins, Field Test Unit Lead, Denver Public Schools
• Sara Krauskopf, Writer, University of Colorado Boulder
• Wayne Wright, Writer, University of Colorado Boulder
• Margee Will, Writer
• Katrina Cable, Writer, Denver Public Schools
• Will Lindsay, Writer, University of Colorado Boulder
• Andres Rodriquez, Writer, Denver Public Schools
• River Suh, Advisor, Science Educators for Equity, Diversity, and Social Justice

inquiryHub, University of Colorado Boulder

• Madison Hammer, Production Manager
• Amanda Howard, Copy Editor
• Nga Hoang, Media Producer
• Erin Howe, Project Manager