Energy, and Growth presents ideas about matter and energy
in living things, primarily human beings, in the first four clusters
of lessons. Cluster 1 (lessons 1-3) deals with why living things
need food; cluster 2 (lessons 4-9) deals with what happens to
food after it enters the body and as it moves to the cells; cluster
3 (lessons 10-13) presents how food is used in human bodies; and
cluster 4 (lessons 14 and 15) is concerned with diet and nutrition.
Idea a: Food provides
the molecules that serve as fuel and building material for all
There is a content
match to the idea. The idea that food provides fuel and building
materials is treated throughout the unit, beginning with the
use of food for energy and continuing later with the use of
food for building material. For example:
- In lesson 1, page
2, after listing many kinds of human activities, the text
says explicitly, "Food stores the energy we need for all of
these life activities." Students then have a firsthand experience
with this idea (Try This, pp. 2-3s), as they burn a marshmallow
and discuss how more light and heat are given off by the burning
marshmallow than by the burning match used to ignite it. Students
are expected to conclude that the extra energy must have come
from the marshmallow. In paragraphs 1, 2, and 5, page 3s,
the text restates the idea that food provides the energy needed
for body functions.
- In lesson 2, the
text explicitly states the idea on page 4s (paragraph 6):
"It's important to eat different kinds of foods because
they contain different kinds of materials our bodies need
for energy and for growing." In the rest of lesson 2,
students are taught what some of these materials are (starch,
sugar, protein, and fat) and find that they are present in
different foods. On page 13s, the text states explicitly (paragraphs
1, 2, and 4) that it is these components of food that the
body must have to grow and obtain energy.
- In lesson 7 (p.
27s), the idea is explicitly stated, again in bold: "These
new substances glucose, amino acids, and fatty acidare
used by the cells as fuel for energy and as building blocks
for making new cell parts." Note that here the term "fuel"
is used for the first time, and it is made clear that the
fuel is used to provide energy.
- In lesson 12 (pp.
46-48s), students model how food particles are digested and
move through the body. Text on page 48s states that amino
acids come from food and can be built back up into proteins,
which are added to cells, which get larger and divide. The
text concludes, "This is how you grow!"
- In lesson 13 (pp.
49-55s), students analyze several hypothetical cases of weight
gain and weight loss. They are to conclude that weight gain
occurs when food (as opposed to water) consumed is greater
than food burned as fuel, and that weight loss occurs when
more food is burned than is consumed.
and Growth initially treats the idea on the substance level,
referring in early lessons to the components of food as "particles."
However, the term "molecules" is introduced to students in lesson
6 (p. 25s) and is used subsequently.
Energy, and Growth focuses primarily on human beings, lesson
12 (p. 48s, Questions 5 and 6) requires students to apply the
idea that food is used for growth to lizards and plants. This
application of the idea that food is used for growth for other
organisms is continued on page 49s, paragraph 1.
Idea b: For the
body to use food for energy and building materials, the food
must first be digested into molecules that are absorbed and
transported to cells.
There is a content
match to this idea. The unit treats the digestion of food in
lessons 5, 6, and 7 in student activities and text. Students
experience firsthand how the starch in oatmeal changes to sugar
when the oatmeal is chewed with saliva (Try This, pp. 19-21s),
how meat tenderizer changes protein (gelatin) (Try This, pp.
22-23s), and how fresh pineapple "digests" gelatin (p. 24s).
The text describes digestion as the breaking down of food components
on page 22s, paragraph 2. On page 25s, the section titled "A
scientific explanation of digestion" summarizes how carbohydrates,
proteins, and fats change in digestion. Yet another explicit
statement of the fact that food must be digested appears on
page 27s, first paragraph.
The absorption of
food molecules is addressed on page 29s, where text states that,
after food is changed chemically into smaller molecules, "The
new molecules pass through very small openings in the wall of
the small intestine and enter the bloodstream." In Try
This, pages 27-29s, students observe that only smaller sand
particles pass through a screen, and that undigested protein
(gelatin) will not go through a sieve, while gelatin that has
been "digested" with meat tenderizer will go through. Students
analyze the components of this model in relation to food passing
from the small intestine into the bloodstream.
of food is addressed on page 27s, paragraphs 3-5, where the
text says that blood vessels are the delivery system of the
body, picking up digested food and carrying it to the cells,
dropping some off as needed. On page 30s, the text puts absorption
and transportation together, explaining how food moves out of
the digestive tract into the bloodstream, dissolving in the
blood as individual molecules and then being pumped to cells
all over the body, "where the materials from food are used."
Finally, the text
in the next to last paragraph on page 33s reiterates how the
digestion, absorption, and transportation of food to cells must
happen before food can be used for energy and building materials.
Idea c: Extracting
energy from food is carried out within the cells.
There is a content
match to this idea. The idea that important processes happen
in cells is introduced in the title of Lesson 3: Where The Action
Is-The Cells (p. 14s). After presenting the prerequisite idea
that the body is made of cells, the text tells students, "All
of your body's cells are living. They need food and oxygen just
like all living things do. They get rid of waste products just
like all living things do...You'd be surprised at the different
activities that go on in cells." (p. 16s) Later in the unit,
the text says that cluster 3 will be about how cells extract
energy in stored glucose and use amino acids to grow and repair
themselves. (p. 33s, last paragraph) In lesson 11, on pp. 42-43s,
text and diagrams repeatedly say the cellular respiration reaction
happens in the cell. Text in the first paragraph says, "...a
very complex set of chemical reactions is going on in cells
that release the stored energy from glucose." A diagram showing
how the molecules react is labeled, "What this looks like in
a cell is this." Text in the last two paragraphs on page 45
states, "The glucose and oxygen molecules react, and the stored
energy is released! The chemical reaction produces water and
carbon dioxide, which leave the cell. This process that cells
use to get energy from food is called cellular respiration."
More details follow on pages 43s and 44s.
Idea d: Animals
get energy from oxidizing their food, releasing some of its
energy as heat.
There is a partial
content match to this idea. The following presentation of idea
d shows which parts of the idea are treated (in bold) and what
vocabulary is used (in brackets) in Food, Energy, and Growth:
Animals get energy from oxidizing [burning] their
food, releasing some of its energy as [and get] heat.
The unit introduces the idea that energy can be produced from
food, in text stating that food stores the energy needed for
life activities (p. 2s). The idea is further developed in lesson
11. Text, equations, and a diagram present the idea that "a
complex set of chemical reactions is going on in cells that
release the stored energy from glucose" (p. 42s). Oxygen is
shown as a component of the reaction in the equations and diagram.
More details are offered on page 43s, where text explains how
producing energy in the body is different from burning a marshmallow
or butter (activities the students have carried out). However,
the idea that in the process of oxidizing food, animals release
some of their energy as heat is not explicitly treated. The
text does state explicitly that some of the energy from food
becomes heat that keeps human body temperature close to 98.6°
F (p. 3s), and that the body needs and produces heat (p. 43s).
However, these statements could be interpreted as implying that
heat is only produced to keep the body warm rather than that
heat production is an inevitable consequence of oxidizing fuel.
Idea e: To burn
food for the release of energy stored in it, oxygen must be
supplied to cells.
and Growth presents the idea that cells need oxygen to burn
food and release the energy stored in it in lessons 7, 9, 10,
and 11. The idea is introduced in lesson 7, where text tells
students, "The blood also carries oxygen from the lungs to the
cells" (p. 30s). In lesson 10, students find that breathing,
pulse rate, and carbon dioxide production increase with exercise.
They answer questions about the meaning of their findings and
are expected to conclude that when they exercise more, they
have to take in more oxygen and the heart has to work faster
to pump to the cells the oxygen they need (pp. 34-35s, Try This,
pp. 36-37s). Summarizing the reactions that release energy from
glucose, the text explicitly states the idea that "Oxygen is
needed to make these reactions occur" and includes oxygen in
all the representations of the cellular respiration reaction
in the chemical equation, the word equation, and the diagram
of how the molecules react (p. 42s).