| Earth Science | Life Science | Physical Science |
About this Evaluation Report Content Analysis Instructional Analysis
| [Explanation] This section examines whether the curriculum material's content aligns with the specific key ideas that have been selected for use in the analysis. |
| [Explanation] This section examines whether the curriculum material develops an evidence-based argument for the key ideas, including whether the case presented is valid, comprehensible, and convincing. |
| [Explanation] This section examines whether the curriculum material makes connections (1) among the key ideas, (2) between the key ideas and their prerequisites, and (3) between the key ideas and other, related ideas. |
| [Explanation] This section notes whether the curriculum material presents any information that is more advanced than the set of key ideas, looking particularly at whether the “beyond literacy” information interrupts the presentation of the grade-appropriate information. |
| [Explanation] This section notes whether the curriculum material presents any information that contains errors, misleading statements, or statements that may reinforce commonly held student misconceptions. |
Idea
b: Plants make their own food, whereas animals obtain food
by eating other organisms. It is stated again in chapter 2, Section 2–2: Characteristics
of Living Things: And, in the context of describing cell processes, the text
includes a diagram of a sugar factory and poses the question,
“Is the diagram a representation of a plant cell or
an animal cell?” (p. 82s). No activities explicitly
focus on the idea. While students observe Euglenas
under a microscope and are told that these organisms are
capable of shifting from being autotrophs to being heterotrophs,
the capabilities of these two kinds of organism are not
contrasted (p. 168s). Earth today is filled with both consumers
and producers. You, for example, are a consumer. You must
eat food in order to obtain energy and important nutrients.
Green plants, on the other hand, are producers. They use
chemicals in their environment and the energy of sunlight
to produce their own food. [p. 43s]
All living things must either take in food
or produce their own food. For most animals, ingestion,
or eating, is as simple as putting food into their mouths.
Green plants do not have to ingest food. Green plants are
able to make their own food. [p. 49s]
Idea c: Matter is transformed in living systems.
Idea
c1: Plants make sugars
from carbon dioxide (in the air) and water. No activities explicitly focus on the idea. Although the
Teacher’s Edition refers to a few activities, none
are explained in terms of this key idea. For example, students
observe that when Elodea is grown in the light, it changes
the color of bromthymol blue solution; however, the focus
of the activity is gas exchange and comparing photosynthesis
and respiration, rather than on the transformation of matter
(p. 232t; Teaching Resources, chapter 9 booklet, pp. 21,
37). In another investigation, students test plant leaves
for starch; but the investigation lacks experimental control
so the transformation of carbon dioxide to sugar or starch
cannot be legitimately concluded (p. 231t; Teaching Resources,
chapter 9 booklet, p. 19). The Teacher’s Edition includes a potentially helpful
question but does not relate it to the key idea. Marginal
notes suggest that the teacher develop the concept of photosynthesis
using the question: “When a seedling with a mass of
only a few grams grows into a tall tree with a mass of several
tons, where does the tree’s increase in mass come
from?” (p. 231t). However, no further suggestions
are given about how to use this question, and the desired
response is not provided. The Teacher’s Edition refers to another potentially
relevant question: “Into which organic compound [of
the carbon cycle in the diagram] does photosynthesis convert
the carbon of [carbon dioxide]?” (p. 232t; Teaching Resources, chapter 9 booklet, p. 21). However, no guidance
is given for how students might respond or how their responses
could be probed further to get at the key idea.Through a complex series of chemical reactions
(which will not be discussed here), the light energy is
used to combine water from the soil with carbon dioxide
from their air. One of the products of the chemical reactions
is food, which is generally in the form of a sugar called
glucose. [p. 232s]
Idea c2: Plants break down the sugars they
have synthesized back into simpler substances—carbon dioxide and water—and
assemble sugars into the plants' body structures, including some energy stores. Glucose can be broken down to release energy….
Glucose can also be changed into other chemicals. Some of
these chemicals are used by a plant for growth and for repair
of its parts. Other chemicals are stored in special areas
in the roots and stems. [p. 232s]
Idea
c3: Other organisms break
down the stored sugars or the body structures of the plants
they eat (or in the animals they eat) into simpler substances
and reassemble them into their own body structures, including
some energy stores. In describing digestion, the text restates the idea but
doesn’t mention energy stores: In Chapter 3: Cells, Tissues, and Organ Systems, in the
context of describing cell parts and functions, the text
notes that inside the mitochondria, simple food substances
are broken down into water and carbon dioxide (p. 78s) and
gives the word and chemical equations for respiration (p.
83s). Two activities are suggested in Teaching Resources, but
neither is explained in terms of this key idea. In the first
activity, students test their breath for carbon dioxide
(p. 82t; Teaching Resources, chapter 3 booklet, p. 23s);
and in the second, they incubate yeast and sugar, smell
the alcohol produced, and observe a color change, which
indicates the production of carbon dioxide (p. 82t; Teaching Resources, chapter 3 booklet, pp. 23, 25). However, students
do not observe what happens when sugar or yeast is not added;
so they cannot legitimately conclude that sugar is transformed
into carbon dioxide and water. Building up and breaking down is a good
way to describe the chemical activities that are essential
to life. During some of these activities, simple substances
combine to form complex substances. These substances are
needed by an organism to grow, store energy, and repair
or replace cells and other body parts. During other activities,
complex substances are broken down, releasing energy and
usable food substances. Together, these chemical activities
are called metabolism…. Metabolism is another characteristic
of living things. [p. 49s]
Getting food into the body is a first step.
Now the process of metabolism can begin. But there is a
lot more to metabolism than just eating. The food must be
digested in order to be used. Digestion is the process by
which food is broken down into simpler substances. Later
some of these simpler substances are reassembled into more
complex materials for use in the growth and repair of the
living thing. [p. 50s]
Idea
c4: Decomposers transform
dead organisms into simpler substances, which other organisms
can reuse. The text then makes explicit the idea that other organisms
can use the substances recycled by decomposers: “These
simpler substances can be used by autotrophs—such
as green plants and blue-green bacteria—to make food”
(p. 141s). In Chapter 7: Fungi, the text mentions that many
species of fungi are decomposers, and poses the question:
“Why can such fungi, along with certain bacteria,
be called ‘the Earth’s cleanup crew’?”
(p. 181s). In Chapter 26: Interactions Among Living Things,
before introducing the concepts of food webs and food chains,
the text reviews the terms “producers,” “consumers,”
and “decomposers” (pp. 668–670s). In the
context of introducing food chains, the text notes that
without decomposers, organisms within an ecosystem could
not survive for long, gives an example of an Antarctic food
chain, and then states the role of decomposers: Two activities focus on the idea. Students observe the
process of making compost in a soda bottle (pp. 841–843s;
Teaching Resources, chapter 26 booklet, pp. 19–23),
and look for signs of decay in a local wooded area (p. 669t;
Teaching Resources, chapter 26 booklet, p. 15). The text states several times that plants use light to
make sugars, but it never makes clear that the sugars become
“energy rich” in the process. For example, in
Chapter 2: The Nature of Life, the text states, “Green
plants…use chemicals in their environment and the
energy of sunlight to produce their own food” (p.
43s), and repeats the statement later in the chapter (p.
50s). In describing the needs of living things, the text
clarifies the idea that food stores energy but stops short
of explaining that the energy stored in food came from the
sun: “Plants use the sun’s light energy to make
food. Some animals feed on plants and in that way obtain
the energy stored in the plants” (p. 55s). Finally,
a single Chapter Review question could probe students’
understanding of photosynthesis, but the question is vague
and the suggested response does not get at the energy transformation
involved: Similarly, Chapter 3: Cells, Tissues, and Organ Systems
does not make explicit the energy transformation that occurs
in the chloroplast: “Chlorophyll captures the energy
of sunlight, which can then be used to help produce food
for the plant cell” (pp. 80–81s). And Chapter
9: Plants With Seeds, in the context of describing photosynthesis,
once again fails to make it explicit that an energy transformation
is involved. The text describes the process using such phrases
as “the sun’s light energy is captured”
and “the light energy is used to combine water from
the soil with carbon dioxide from the air,” and it
presents the word equation that does not indicate that the
product glucose is energy rich (p. 232s). As in its earlier
presentation, the text explains that glucose can be broken
down to release energy, but it does not point out that the
energy in glucose comes from some of the light energy that
was transformed (p. 232s). Because many students have difficulty
understanding that energy cannot be created or destroyed,
they will probably think that the glucose energy is a “new”
energy (Gayford,
1986). The material also includes two relevant activities, but
neither focuses on energy transformation. Students grow
plants under cellophane sheets of different colors and observe
the effect of the color of the cellophane on growth (p.
43t). While this activity can help students understand the
idea examined, the energy transformations in plants is not
mentioned. In chapter 9, students grow Elodea in the dark
and in the light, and observe that only the Elodea grown
in the light removes carbon dioxide from its medium (pp.
801–802s). However, the Analysis and Conclusions questions
focus on matter rather than energy transformation.
What happens to the leaves that people rake
in the fall?
What happens to leaves that fall in
the forest?
Whether leaves fall to the forest
floor or are composted in a backyard, how do the leaves
decompose?
Why does a leaf decompose?
What would happen if all the bacteria
suddenly disappeared from the Earth? [p. 140t]The “end” of a food chain is
connected to the “beginning” by decomposers.
In the Antarctic food chain, decomposers break down the
body of the killer whale when it dies. This makes matter
in the form of nutrients available to the producers. [p.
670s]
Idea
d: Energy is transformed in living systems.
Idea d1: Plants use the energy from light
to make "energy-rich" sugars.
Question: Defend this statement: All plants
and animals get their energy from the sun. [p. 67s, Concept
Mastery, item 4]
Suggested response: Plants produce food
by using raw materials obtained from the air, soil, and
water in combination with energy from the sun…. [p.
66t]
Idea
d2: Plants get energy
by breaking down the sugars, releasing some of the energy
as heat. In Chapter 9: Plants With Seeds, after dealing with photosynthesis,
the student text states only that glucose can be broken
down to release energy (p. 232s). None of the statements
about respiration indicate that heat is released.
Earlier you learned that energy
is released when simple food substances such as sugars are
broken down inside the mitochondria. The process in which
simple food substances such as glucose are broken down,
and the energy they contain is released is called respiration.
Because living things need a continuous supply of energy,
respiration is performed constantly by all living
things. [p. 82s]
Idea
d3: Other organisms get
energy to grow and function by breaking down the consumed
body structures to sugars and then breaking down the sugars,
releasing some of the energy into the environment as heat. In Chapter 3: Cells, Tissues, and Organ Systems, the text
states that “Inside the mitochondria, simple food
substances such as sugars are broken down into water and
carbon dioxide” and that energy is released (p. 78s).
Much later, in Chapter 26: Interactions Among Living Things,
the text describes the loss of energy at each level in a
food web but does not indicate that the energy is released
as heat: “At each feeding level, organisms use the
energy they obtain to digest their food, reproduce, move,
grow, and carry out other life activities. What does this
mean for living things at higher feeding levels? It means
that there is less energy available to them” (pp.
671–672s).
DIGESTION Getting
food into the body is a first step. Now the process of metabolism
can begin. But there is a lot more to metabolism than just
eating. The food must be digested in order to be used. Digestion
is the process by which food is broken down into simpler
substances….
RESPIRATION All
living things require energy to survive. To obtain energy,
living things combine oxygen with the products of digestion
(in animals) or the products of photosynthesis (in green
plants). The energy is used to do the work of the organism.
The process by which living things take in oxygen and use
it to produce energy is called respiration. You get the
energy you need by combining the foods you eat with the
oxygen you breathe. [p. 50s]
Idea
e: Matter and energy are transferred from one organism
to another repeatedly and between organisms and their
physical environment.
Question: Defend this statement: All plants
and animals get their energy from the sun. [p. 67s, Concept
Mastery, item 4]
Suggested response: Plants produce
food by using raw materials obtained from the air, soil,
and water in combination with energy from the sun. The plants
then obtain energy by breaking down these foods through
respiration. Animals either eat plants for food or eat other
animals that eat plants. In either case, the animal produces
energy through respiration by combining the food with oxygen.
[p. 66t]
With respect to the idea that plants transform light energy into chemical energy in sugars (Idea d1), the material explains that light energy is used in photosynthesis, and then that glucose can be broken down to release energy. But it never points out that the energy in glucose comes from some of the light energy that is captured by the plants (p. 232s). As many students have difficulty understanding that energy cannot be created or destroyed, they will probably think that the light energy “disappeared,” and that glucose energy is a “new” energy.
A different example is related to the idea that the sugars that are made by plants can be assembled into the plants’ body structures (Idea c2). In chapter 9, the text describes parts of plants and gives examples of plants that store food in their roots and stems (pp. 224–230s) but does not mention where this stored food comes from. Later, when the food-making process is recounted, the Teacher’s Edition states:
Our understanding of photosynthesis is the result of the same question being asked for thousands of years: When a seedling with a mass of only a few grams grows into a tall tree with a mass of several tons, where does the tree’s increase in mass come from? [p. 231t]
However, while this question can be helpful, there is no follow-up to it. The student text explains briefly what happens to the sugar formed in photosynthesis:
Glucose can also be changed into other chemicals. Some of these chemicals are used by a plant for growth and for repair of its parts. Other chemicals are stored in special areas in the roots and stems. [p. 232s]
Unfortunately, the text does not go back to answer the question: “Where does the tree’s increase in mass come from?” Nor does it make clear that the food stored in roots, stems, and leaves and the “chemicals” stored in these body parts are essentially the same thing.
However, the material does refrain from including more sophisticated material in its treatment of photosynthesis:
In photosynthesis, the sun’s energy is captured by chlorophyll, which is the green pigment you read about in Chapter 8. Through a complex series of chemical reactions (which will not be discussed here), the light energy is used to combine water from the soil which carbon dioxide from the air. One of the products of the chemical reactions is food, which is generally in the form of a sugar called glucose. [p. 232s]
The text does not present light and dark reactions of photosynthesis or details of respiration.
The teams’ collective findings, presented below, should be taken as having general applicability to all of the evaluated materials, not complete and specific applicability in toto to any one of them.
Identified errors occur most frequently in drawings and other diagrams. They take the form of representations that are likely to either give rise to or reinforce misconceptions commonly held by students. Following are life science examples of the kinds of misleading illustrative materials of most concern to the evaluation teams:
- Diagrams of energy pyramids that indicate decreases in energy (without indicating that the energy is given off as heat) can reinforce students’ misconception that energy is not conserved.
- Diagrams and explanations that show the reciprocal nature of respiration and photosynthesis can reinforce the misconception that only animals respire—and that plants do not. Furthermore, emphasizing the notion that these processes are reciprocal or balance one another fails to convey that the rate of photosynthesis is far more than that of respiration. Consequently, plants produce enough food (and oxygen) during photosynthesis both for their own needs and for the needs of other organisms.
- Diagrams of nutrient cycles in biological systems, such as the carbon-oxygen cycle or the nitrogen cycle, often misrepresent the transformation of matter—showing, for example, atoms of carbon in one form but not in others. By failing to show a particular element throughout the cycle, a text can reinforce the misconception that matter can disappear in one place and reappear in another, as opposed to simply changing forms.
The use of imprecise or inaccurate language is problematic in text and teacher materials, not solely in illustrations. In life science, one significant problem is that imprecise language in explanations of energy transformations can reinforce students’ common misconception that matter and energy can be interconverted in everyday chemical reactions. For example, presenting the overall equation for cellular respiration in which energy appears as a product without indicating where the energy was at the start can lead students to conclude that matter is converted to energy. Similarly, presenting the overall equation for photosynthesis in which energy appears only as a reactant can lead them to conclude that energy has been converted into matter.
