Key Idea 1: Living things are both similar to and different from each other and from nonliving things.

PERFORMANCE INDICATOR 1.1: Explain how diversity of populations within ecosystems relates to the stability of ecosystems.

MAJOR UNDERSTANDING 1.1a: Populations can be categorized by the function they serve. Food webs identify the relationships among producers, consumers, and decomposers carrying out either autotropic or heterotropic nutrition.

MAJOR UNDERSTANDING 1.1b: An ecosystem is shaped by the nonliving environment as well as its interacting species. The world contains a wide diversity of physical conditions, which creates a variety of environments.

MAJOR UNDERSTANDING 1.1c: In all environments, organisms compete for vital resources. The linked and changing interactions of populations and the environment compose the total ecosystem.

MAJOR UNDERSTANDING 1.1d: The interdependence of organisms in an established ecosystem often results in approximate stability over hundreds and thousands of years. For example, as one population increases, it is held in check by one or more environmental factors or another species.

MAJOR UNDERSTANDING 1.1e: Ecosystems, like many other complex systems, tend to show cyclic changes around a state of approximate equilibrium.

MAJOR UNDERSTANDING 1.1f: Every population is linked, directly or indirectly, with many others in an ecosystem. Disruptions in the numbers and types of species and environmental changes can upset ecosystem stability.

Key Idea 5: Organisms maintain a dynamic equilibrium that sustains life.

PERFORMANCE INDICATOR 5.1: Explain the basic biochemical processes in living organisms and their importance in maintaining dynamic equilibrium.

MAJOR UNDERSTANDING 5.1a: The energy for life comes primarily from the Sun. Photosynthesis provides a vital connection between the Sun and the energy needs of living systems.

MAJOR UNDERSTANDING 5.1b: Plant cells and some one-celled organisms contain chloroplasts, the site of photosynthesis. The process of photosynthesis uses solar energy to combine the inorganic molecules carbon dioxide and water into energy-rich organic compounds (e.g., glucose) and release oxygen to the environment.

Key Idea 6: Plants and animals depend on each other and their physical environment.

PERFORMANCE INDICATOR 6.1: Explain factors that limit growth of individuals and populations.

MAJOR UNDERSTANDING 6.1a: Energy flows through ecosystems in one direction, typically from the Sun, through photosynthetic organisms including green plants and algae, to herbivores to carnivores and decomposers.

MAJOR UNDERSTANDING 6.1b: The atoms and molecules on the Earth cycle among the living and nonliving components of the biosphere. For example, carbon dioxide and water molecules used in photosynthesis to form energy-rich organic compounds are returned to the environment when the energy in these compounds is eventually released by cells. Continual input of energy from sunlight keeps the process going. This concept may be illustrated with an energy pyramid.

MAJOR UNDERSTANDING 6.1d: The number of organisms any habitat can support (carrying capacity) is limited by the available energy, water, oxygen, and minerals, and by the ability of ecosystems to recycle the residue of dead organisms through the activities of bacteria and fungi.

MAJOR UNDERSTANDING 6.1e: In any particular environment, the growth and survival of organisms depend on the physical conditions including light intensity, temperature range, mineral availability, soil/rock type, and relative acidity (pH).

MAJOR UNDERSTANDING 6.1f: Living organisms have the capacity to produce populations of unlimited size, but environments and resources are finite. This has profound effects on the interactions among organisms.

MAJOR UNDERSTANDING 6.1g: Relationships between organisms may be negative, neutral, or positive. Some organisms may interact with one another in several ways. They may be in a producer/consumer, predator/prey, or parasite/host relationship; or one organism may cause disease in, scavenge, or decompose another.

PERFORMANCE INDICATOR 6.2: Explain the importance of preserving diversity of species and habitats.

MAJOR UNDERSTANDING 6.2a: As a result of evolutionary processes, there is a diversity of organisms and roles in ecosystems. This diversity of species increases the chance that at least some will survive in the face of large environmental changes. Biodiversity increases the stability of the ecosystem.

PERFORMANCE INDICATOR 6.3: Explain how the living and nonliving environments change over time and respond to disturbances.

MAJOR UNDERSTANDING 6.3a: The interrelationships and interdependencies of organisms affect the development of stable ecosystems.

MAJOR UNDERSTANDING 6.3b: Through ecological succession, all ecosystems progress through a sequence of changes during which one ecological community modifies the environment, making it more suitable for another community. These long-term gradual changes result in the community reaching a point of stability that can last for hundreds or thousands of years.

MAJOR UNDERSTANDING 6.3c: A stable ecosystem can be altered, either rapidly or slowly, through the activities of organisms (including humans), or through climatic changes or natural disasters. The altered ecosystem can usually recover through gradual changes back to a point of longterm stability.

Key Idea 7: Human decisions and activities have had a profound impact on the physical and living environment.

MAJOR UNDERSTANDING 7.1b: Natural ecosystems provide an array of basic processes that affect humans. Those processes include but are not limited to: maintenance of the quality of the atmosphere, generation of soils, control of the water cycle, removal of wastes, energy flow, and recycling of nutrients. Humans are changing many of these basic processes and the changes may be detrimental.

MAJOR UNDERSTANDING 7.1c: Human beings are part of the Earth’s ecosystems. Human activities can, deliberately or inadvertently, alter the equilibrium in ecosystems. Humans modify ecosystems as a result of population growth, consumption, and technology. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening current global stability, and if not addressed, ecosystems may be irreversibly affected.

PERFORMANCE INDICATOR 7.2: Explain the impact of technological development and growth in the human population on the living and nonliving environment.

MAJOR UNDERSTANDING 7.2a: Human activities that degrade ecosystems result in a loss of diversity of the living and nonliving environment. For example, the influence of humans on other organisms occurs through land use and pollution. Land use decreases the space and resources available to other species, and pollution changes the chemical composition of air, soil, and water.

KEY IDEA 1: The central purpose of scientific inquiry is to develop explanations of natural phenomena in a continuing and creative process

PERFORMANCE INDICATOR 1.2: Hone ideas through reasoning, library research, and discussion with others, including experts

PERFORMANCE INDICATOR 1.3: Work towards reconciling competing explanations; clarify points of agreement and disagreement

KEY IDEA 3: The observations made while testing proposed explanations, when analyzed using conventional and invented methods, provide new insights into natural phenomena.

PERFORMANCE INDICATOR 3.1: Use various methods of representing and organizing observations (e.g. diagrams, tables, charts, graphs, equations matrices) and insightfully interpret the organized data

Reading: Key Ideas and Details

Determine the central ideas or conclusions of a text; trace the text’s explanation or depiction of a complex process, phenomenon, or concept; provide an accurate summary of the text.

Reading: Craft and Structure

Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 9–10 texts and topics.

Reading: Integration of Knowledge and Ideas

Translate quantitative or technical information expressed in words in a text into visual form (e.g., a table or chart) and translate information expressed visually or mathematically (e.g., in an equation) into words.

Reading: Integration of Knowledge and Ideas

Compare and contrast findings presented in a text to those from other sources (including their own experiments), noting when the findings support or contradict previous explanations or accounts.

Reading: Range of Reading and Level of Text Complexity

By the end of grade 10, read and comprehend science/technical texts in the grades 9–10 text complexity band independently and proficiently

Writing: Range of Writing

Write routinely over extended time frames (time for reflection and revision) and shorter time frames (a single sitting or a day or two) for a range of discipline-specific tasks, purposes, and audiences.