Life Science—Biology Concept and Skill Progressions

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Before Instruction

Conceptual “Stepping Stones”

Central Concepts & Skills

Before instruction, students often believe and can:

Students who view the world in this way believe and can:

Students who fully understand this topic believe and can:





High school

Interdependent Relationships in Ecosystems

Students are able to consider if an organism is alive and where it lives. Students’ initial criteria for life are based on overt resemblance to familiar organisms, especially people and pets; Students judge humans and mammals as living.

Students view organisms as existing for the benefit of humans.

Initial criteria for habitat are based on analogy to home.

Students consider places where living organisms are seen as their homes.

Students associate organisms to physical spaces with respect to general location (e.g., ground, air, pond, forest, lawn).

Interdependent relationships in Ecosystems

Students are able to identify organisms as functional units, quantify what it means to “eat” and “be eaten.”

Students can describe features and/or behaviors of living and non-living components of places.

Students notice relative frequencies of organisms in one or more places.

Students expand criteria for life to include ability to move on its own, eating, and/ or evidence of growth.

Students can observe macroscopic attributes by use of simple tools, such as hand lens or dissecting scopes and can describe the advantage of macroscopic attributes that allow the organism to use the resources in a habitat (behavior or structure).

Students notice that place or time may be associated with the presence or absence of particular organisms.

Students understand that animals depend on plants and other animals for food.

Possible misconceptions

Students are able to consider the needs of organisms but

students may relate organisms to habitat via organism’s needs and ways of satisfying those needs. The relationship is perceived to be unidirectional; the habitat satisfies needs.

Interdependent relationships in Ecosystems

Students are able to identify and qualitatively and quantitatively describe a group/population of organisms, noting either similarities or differences.

Students are able to describe change within a group of organisms by characterizing transition in attributes, counts, or stages.

Students are able to compare organisms and their attributes and their suitability to a habitat and understand that organisms can survive only in environments in which their needs are met. (NRC Framework)

Students understand that the relationships between organisms and ecosystems are complex and interacting (bidirectional) and are able to describe ways in which organisms affect ecosystems by altering ecosystem structures and functions.

Students are able to characterize interactions among organisms and environments and are able to develop hypotheses about the mechanisms by which non-living qualities of habitat (such as light, moisture) affect resources required for survival.

Students are able to describe, measure, and model important ecosystem components that are not directly visible, such as nutrients and microbes, and climate.

When the environment changes, some plants and animals survive and reproduce; others move to new locations, and some die. (NRC Framework)

Interdependent relationships in Ecosystems

Students understand that populations are made of individuals that live, grow, reproduce, and die.

Students view organisms and populations of organisms as dependent on their interactions with other living things (biotic), and their interactions with non-living (abiotic) factors in the environment. (NRC Framework)

In any environment, organisms and populations with similar requirements for food, water, air, or other resources may compete with each other for limited resources. The growth and reproduction of an organism and of populations will be constrained by access to these limited resources. (NRC Framework)

The interactions between organisms in a given environment may be competitive or mutually beneficial. Competitive interactions may reduce the number of organisms or eliminate populations of organisms. Mutually beneficial interactions may become so interdependent that each requires the other for survival. (NRC Framework)

Students are able to use multiple resources to draw an ecosystem (forest, desert, marine, stream, field, or other) which includes organisms at all trophic levels, and show how these organisms interact.

Students understand are able to characterize limits and their effects on an ecosystem.

Students are able to describe how disruptions to the physical (abiotic) or biological (biotic) components of an ecosystem impact other components of an ecosystem. (NRC Framework)

Students can represent adaptation as a trade-off between costs and benefits and relate this to change at the organism level.
Possible misconception

Middle school students often conflate systems and cycles as it relates to ecosystem processes.

Interdependent relationships in Ecosystems

Students understand there are many kinds of organisms in many different places and this composition of life changes over time.

Students understand organisms exist as populations whose compositions depend on history, biogeochemical cycles, and space (geology).1

Students understand populations in terms of species classifications.

Students understand that the factors guiding the presence and absences of organisms are complex and can be linked to concepts of biodiversity, evolution, biogeochemical cycles, and geology.

Students know that a multitude of organisms populate a particular habitat and are embedded within a complex system. They understand that what affects one population of organisms is also likely to affect the other populations that live in that habitat. Changes in habitat are apt to affect the functioning of the ecology and thus the chance that individual organisms will survive and replicate. (Catley et al, 2005)

Students understand that ecosystems have carrying capacities, which are limits to the numbers and types of organisms and populations an ecosystem can support. These limits are a result of such factors as availability of biotic and abiotic resources, and biotic challenges such as predation, competition, and disease. (NRC Framework)

Students understand and are able to differentiate between systems and cycles: systems are sets of interacting components that operate on an aggregate level to achieve a function. Cycles are types of systems that repeat (life cycle, carbon cycle, etc); however, not all systems are cycles. Systems and cycles are both dynamic.2

Students understand how to use models, data visualization, control, uncertainty, and multivariable study in terms of ecosystem dynamics and interactions.3

Flow of Matter and Energy Transfer in Ecosystems

Children understand that humans breathe oxygen and they associate oxygen with air.

Possible Misconceptions:

Young children think of food as anything that is edible.

Later, children think of food as “anything taken into an organism’s body, including water, minerals, and, in the case of plants, carbon dioxide or even sunlight” (Driver, et al., 1994, p. 27).
Students have difficulty with food webs, cycles, and systems: Young students are likely to think that feeding relations are unidirectional: they view an organism as feeding on organisms but not as being food for other organisms. In the same respect, they have difficulty in considering each organism is a food chain as occupying more than one role. (CPRE-PCK)
Young children think that dead things just disappear; they think of decomposition as the total or partial disappearance of matter.

Flow of Matter and Energy Transfer in Ecosystems

Living things get the materials they need to grow and survive from the environment.

(NRC Framework)

Many materials from living things are used again by other living things. (NRC Framework)

Possible Misconceptions:

The scientific definition of food is often confused with its common usage. In everyday usage, “food is whatever nutrients plants and animals must take in if they are to grow and survive.

Students understand that plants absorb water from the soil but may think that this is the main process for growth (Barker & Carr, 1989).

Students understand that plants depend on air, water, and light to grow but will likely consider all these components as well as heat (from the sun), soil, minerals, and fertilizer as food.4

Flow of Matter and Energy Transfer in Ecosystems

Students are able to explain that food of almost all kinds of animals can be traced back to plants. Some animals eat plants for food. Other animals eat animals that eat plants.5 (NRC Framework)

Students are able to represent positions that an organisms occupies in a food chain and the interactions it has with other organisms: what an organism eats, and what eats the organism.

Students understand that some organisms such as fungi and bacteria operate as decomposers. Decomposition eventually recycles some materials back to the soil for plants to use, and to repeat the food chain cycle. (NRC Framework)

Many children have some basic understanding that food is broken down, that acid breaks down the food, and that some kind of “goodness” is taken into the body from the food; Students understand the function of the organs and have a “biological basis” for understanding the digestive system
Possible Misconceptions:

Students understand that “energy is obtained from food” and “digestion is the breakdown of food,” but students can misconceive that “digestion is the process that releases usable energy from food,” Students confuse ideas about food, plant, and animal nutrition, and digestion and the release of energy from food.6 (CPRE-PCK)

Students often think that plants get their food from the soil. This is a very common misconception found by multiple researchers and summarized by Bell (1985). It is simply easier for students to believe that roots are used for feeding instead of coming to understand that photosynthesis is the process by which plants can produce their own food.7

Students can confuse ideas of plant photosynthesis and respiration: many children have a “`plant breathing-animal breathing’ model: that animals breathe in oxygen and breathe out carbon dioxide, whereas plants breathe in carbon dioxide and breathe out oxygen” (Driver et al., 1994, p. 33).7

Students are uncertain that a gaseous element is a real substance with mass and weight—an essential notion in understanding how plants use carbon dioxide. (CPRE-PCK)

Students may think that plants use heat (instead of light energy) from the sun as the energy for photosynthesis. Most students considered that the sun is one among “many sources of energy for plants, others being soil, minerals, water, air, and wind” (Driver et al., 1994, p. 33).7

Flow of Matter and Energy Transfer in Ecosystems

Students understand that all ecosystem processes rely on energy movement from the sun to organisms

Students can distinguish between food chains and food webs: A food chain is the transfer of energy from primary producers (e.g. plants) through a series of organisms that eat and are eaten. A food web depicts “the feeding relationships between organisms in an ecosystem.; a series of interconnected food chains (CPRE-PCK)

Students understand that light contains energy and the light energy captured by plants (producers) during photosynthesis is utilized to facilitate a chemical reaction between carbon dioxide and water to produce sugar and oxygen.7

Students are able to identify sugar as food the photosynthetic organism has created for itself and that this food is used as both fuel and building material.

Students are able to explain that oxygen is simply a waste product of the process of photosynthesis rather than something that is created just for humans. (CPRE-PCK)

Students are able to define the terms producer and consumer and relate these terms to organisms and connections drawn in a food web.

Students understand the biological role of food- that food is used as fuel and building material in all organisms in a food chain. Plants (producers), animals (consumers), and decomposers use food (e.g., sugar, protein, fat) as a source of energy and building material. Not all food is converted to useful energy-some dissipates as heat.

Students are able to describe, in terms of energy, why there are only a certain number of producers, consumers, and top consumers in an ecosystem. They are able to explain from where the energy in the system originates and where each organism acquires the energy and molecular building blocks for life.
Possible Misconceptions:

Students may start out thinking that respiration is an exchange of gases involving only the lungs and the heart but typically fail to link respiration to metabolism or the conversion of food to energy.

Students think that plants do not respire or they respire only in the dark and only through the pores of their leaves. They do not think of respiration in plants as an energy conversion process. Students think that photosynthesis is the energy-providing process of plants. 7

Students typically fail to connect chemical elements such as hydrogen, oxygen, and carbon to the building blocks upon which the body is built. Due to this lack of understanding about the chemical nature of life, students think that rotted material enriches or fertilizes the soil but they don’t think of organic matter changing to mineral matter during decay or the role that micro-organisms play as decomposers and recyclers of essential elements of life.

Flow of Matter and Energy Transfer in Ecosystems

Students are able to explain that an autotroph is able to create organic compounds using simple nonorganic molecules (e.g., carbon dioxide) using energy (i.e., light or chemical reactions).

Students understand that autotrophic organisms start off food chains. Students understand that autotrophic organisms subsequently become food for other animals to consume, which can become food for other animals in return. (CPRE-PCK)

Students understand that living things are made up of essential elements, such as oxygen, hydrogen, and carbon, which combine to form biotic and abiotic molecules such as proteins, carbohydrates, and lipids, which are vital to life processes.

Students understand energy is released in chemical reactions during cellular respiration in all organisms. In this process that occurs in both plants and animals, sugar molecules react with oxygen molecules to produce water molecules and carbon dioxide molecules. In addition, during respiration chemical energy is released and can then be transformed into other types of energy and used for a variety of functions such as movement and to build structures; Students are able to trace carbon through ecosystems and explain the multiple processes that are involved in energy movement from the sun to organisms and back to the abiotic components.

Students understand that matter and energy are conserved in the food chain including decomposition: the molecules from the decomposed organisms become part of the abiotic community and are recycled. The flow of matter and energy in a food chain obey the laws of physics and chemistry.8

Possible Misconception:

Students view these changes brought about by eating as a chemical processes in which matter is transformed from one type of substance to another during digestion, however, high school students to have a limited understanding of the role of food to provide both energy and building materials for the body.9 (CPRE-PCK)






High school

Key Vocabulary

Animal, plant, habitat

Organism, resource, bacteria, fungi, decomposer, recycle, ecosystem

Abiotic, biotic, population, producer, consumer, competitive, mutually beneficial, interdependent, dynamic, stability, resilience, photosynthesis, respiration, metabolism, equilibrium, system, cycle, molecule, atoms

Photosynthesis, respiration, catabolism, dissipate, chlorophyll, chloroplast, organelle, trophic level, autotrophic, heterotrophic, chemical energy, mechanical energy, conservation of energy and matter

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