Prerequisites

This unit builds on the following life science concepts from the NGSS DCIs in the 6–8 grade band.

LS1.C: Organization for Matter and Energy Flow in Organisms

• Plants, algae (including phytoplankton), and many microorganisms use the energy from light to make sugars (food) from carbon dioxide from the atmosphere and water through the process of photosynthesis, which also releases oxygen. These sugars can be used immediately or stored for growth or later use.

• Within individual organisms, food moves through a series of chemical reactions in which it is broken down and rearranged to form new molecules, to support growth, or to release energy.

LS2.A: Interdependent Relationships in Ecosystems

• Organisms, and populations of organisms, are dependent on their environmental interactions both with other living things and with nonliving factors.

• In any ecosystem, organisms and populations with similar requirements for food, water, oxygen, or other resources may compete with each other for limited resources, access to which consequently constrains their growth and reproduction.

• Growth of organisms and population increases are limited by access to resources.

LS2.B: Cycles of Matter and Energy Transfer in Ecosystems

• Food webs are models that demonstrate how matter and energy is transferred between producers, consumers, and decomposers as the three groups interact within an ecosystem. Transfers of matter into and out of the physical environment occur at every level. Decomposers recycle nutrients from dead plant or animal matter back to the soil in terrestrial environments or to the water in aquatic environments. The atoms that make up the organisms in an ecosystem are cycled repeatedly between the living and nonliving parts of the ecosystem.

LS4.D: Biodiversity and Humans

• Changes in biodiversity can influence humans’ resources, such as food, energy, and medicines, as well as ecosystem services that humans rely on—for example, water purification and recycling.

The unit also expects some familiarity and practice with the following focal science and engineering practices and crosscutting concepts at the 6-8 grade band level

Defining problems

• Define a design problem that can be solved through the development of an object, tool, process, or system and includes multiple criteria and constraints, including scientific knowledge that may limit possible solutions.

Developing and using models

• Evaluate limitations of a model for a proposed object or tool.

• Develop or modify a model—based on evidence—to match what happens if a variable or component of a system is changed.

• Use and/or develop a model of simple systems with uncertain and less predictable factors.

• Develop and/or revise a model to show the relationships among variables, including those that are not observable but predict observable phenomena.

• Develop and/or use a model to predict and/or describe phenomena.

• Develop a model to describe unobservable mechanisms.

• Develop and/or use a model to generate data to test ideas about phenomena in natural or designed systems, including those representing inputs and outputs, and those at unobservable scales.

Designing solutions

• Apply scientific ideas or principles to design, construct, and/or test a design of an object, tool, process, or system.

• Undertake a design project, engaging in the design cycle, to construct and/or implement a solution that meets specific design criteria and constraints.

• Optimize performance of a design by prioritizing criteria, making trade-offs, testing, revising, and retesting.

Engaging in argument from evidence

• Compare and critique two arguments on the same topic and analyze whether they emphasize similar or different evidence and/or interpretations of facts.

• Respectfully provide and receive critiques about one’s explanations, procedures, models, and questions by citing relevant evidence and posing and responding to questions that elicit pertinent elaboration and detail.

• Construct, use, and/or present an oral and written argument supported by empirical evidence and scientific reasoning to support or refute an explanation or a model for a phenomenon or a solution to a problem.

• Make an oral or written argument that supports or refutes the advertised performance of a device, process, or system, based on empirical evidence concerning whether or not the technology meets relevant criteria and constraints.

Obtaining, evaluating, and communicating information

• Critically read scientific texts adapted for classroom use to determine the central ideas and/or obtain scientific and/or technical information to describe patterns in and/or evidence about the natural and designed world(s).

• Integrate qualitative and/or quantitative scientific and/or technical information in written text with that contained in media and visual displays to clarify claims and findings.

• Gather, read, and synthesize information from multiple appropriate sources and assess the credibility, accuracy, and possible bias of each publication and methods used, and describe how they are supported or not supported by evidence.

• Evaluate data, hypotheses, and/or conclusions in scientific and technical texts in light of competing information or accounts.

• Communicate scientific and/or technical information (e.g., about a proposed object, tool, process, system) in writing and/or through oral presentations.

Scale, proportion, and quantity

• Time, space, and energy phenomena can be observed at various scales using models to study systems that are too large or too small.

• Proportional relationships (e.g., speed as the ratio of distance traveled to time taken) among different types of quantities provide information about the magnitude of properties and processes.

• Phenomena that can be observed at one scale may not be observable at another scale.

• The observed function of natural and designed systems may change with scale.

• Scientific relationships can be represented through the use of algebraic expressions and equations.

Systems and system models

• Models can be used to represent systems and their interactions—such as inputs, processes, and outputs—and energy and matter flows within systems.

• Systems may interact with other systems; they may have subsystems and be a part of larger complex systems.

• Models are limited in that they only represent certain aspects of the system under study.

Energy and matter

• Matter is conserved because atoms are conserved in physical and chemical processes.

• Energy may take different forms (e.g., energy in fields, thermal energy, energy of motion).

• Within a natural system, the transfer of energy drives the motion and/or cycling of matter.

• The transfer of energy can be tracked as energy flows through a natural system.