The Nature of Science and Technology
Students design and carry out increasingly sophisticated investigations. They understand the reason for isolating
and controlling variables in an investigation. They realize that scientific knowledge is subject to change as new evidence
arises. They examine issues in the design and use of technology, including constraints, safeguards, and trade-offs.
The Scientific View of the World
8.1.1 Recognize that and describe how
scientific knowledge is subject to modification as new information challenges prevailing theories and as a new theory* leads
to looking at old observations in a new way.
8.1.2 Recognize and explain that some
matters cannot be examined usefully in a scientific way.
* theory: an explanation supported by
8.1.3 Recognize and describe that if
more than one variable changes at the same time in an experiment, the outcome of the experiment may not be attributable to
any one of the variables.
The Scientific Enterprise
8.1.4 Explain why accurate record keeping,
openness, and replication are essential for maintaining an investigator’s credibility with other scientists and society.
8.1.5 Explain why research involving
human subjects requires that potential subjects be fully informed about the risks and benefits associated with the research
and that they have the right to refuse to participate.
Technology and Science
8.1.6 Identify the constraints that
must be taken into account as a new design is developed, such as gravity and the properties of the materials to be used.
8.1.7 Explain why technology issues
are rarely simple and one-sided because contending groups may have different values and priorities.
8.1.8 Explain that humans help shape
the future by generating knowledge, developing new technologies, and communicating ideas to others.
Students use computers to organize and compare information. They perform calculations and determine the appropriate
units for the answers. They weigh the evidence for or against an argument, as well as the logic of the conclusions.
Computation and Estimation
8.2.1 Estimate distances and travel
times from maps and the actual size of objects from scale drawings.
8.2.2 Determine in what units, such
as seconds, meters, grams, etc., an answer should be expressed based on the units of the inputs to the calculation.
Manipulation and Observation
8.2.3 Use proportional
reasoning to solve problems.
8.2.4 Use technological
devices, such as calculators and computers, to perform calculations.
8.2.5 Use computers
to store and retrieve information in topical, alphabetical, numerical, and keyword files and create simple files of students’
8.2.6 Write clear, step-by-step instructions
(procedural summaries) for conducting investigations, operating something, or following a procedure.
8.2.7 Participate in group discussions
on scientific topics by restating or summarizing accurately what others have said, asking for clarification or elaboration,
and expressing alternative positions.
8.2.8 Use tables,
charts, and graphs in making arguments and claims in, for example, oral and written presentations about lab or fieldwork.
Critical Response Skills
8.2.9 Explain why arguments are invalid
if based on very small samples of data, biased samples, or samples for which there was no control sample.
8.2.10 Identify and criticize the reasoning
in arguments in which fact and opinion are intermingled or the conclusions do not follow logically from the evidence given,
an analogy is not apt, no mention is made of whether the control group is very much like the experimental group, or all members
of a group are implied to have nearly identical characteristics that differ from those of other groups.
The Physical Setting
Students collect and organize data to identify relationships between physical objects, events, and processes.
They use logical reasoning to question their own ideas as new information challenges their conceptions of the natural world.
8.3.1 Explain that large numbers of
chunks of rock orbit the sun and some of this rock interacts with Earth.
Earth and the Processes That Shape It
8.3.2 Explain that the slow movement
of material within Earth results from heat flowing out of the deep interior and the action of gravitational forces on regions
of different density*.
8.3.3 Explain that the solid crust of
Earth, including both the continents and the ocean basins, consists of separate plates that ride on a denser, hot, gradually
deformable layer of earth. Understand that the crust sections move very slowly, pressing against one another in some places,
pulling apart in other places. Further understand that ocean-floor plates may slide under continental plates, sinking deep
into Earth, and that the surface layers of these plates may fold, forming mountain ranges.
8.3.4 Explain that earthquakes often
occur along the boundaries between colliding plates, and molten rock from below creates pressure that is released by volcanic
eruptions, helping to build up mountains. Understand that under the ocean basins, molten rock may well up between separating
plates to create new ocean floor. Further understand that volcanic activity along the ocean floor may form undersea mountains,
which can thrust above the ocean’s surface to become islands.
8.3.5 Explain that everything on or
anywhere near Earth is pulled toward Earth’s center by a gravitational force.
8.3.6 Understand and explain that the
benefits of Earth’s resources, such as fresh water, air, soil, and trees, are finite and can be reduced by using them
wastefully or by deliberately or accidentally destroying them.
8.3.7 Explain that the atmosphere and
the oceans have a limited capacity to absorb wastes and recycle materials naturally.
* density: the density of a sample is
the sample’s mass* divided by its volume
* mass: a measure of how much matter*
is in an object
* matter: anything that has mass and
takes up space
Matter and Energy*
8.3.8 Explain that all matter is made
up of atoms* which are far too small to see directly through an optical microscope. Understand that the atoms of any element*
are similar but are different from atoms of other elements. Further understand that atoms may stick together in well-defined
molecules or may be packed together in large arrays. Also understand that different arrangements of atoms into groups comprise
8.3.9 Demonstrate, using drawings and
models, the movement of atoms in a solid*, liquid*, and gaseous* state. Explain that atoms and molecules are perpetually in
8.3.10 Explain that increased temperature
means that atoms have a greater average energy of motion and that most gases expand when heated.
8.3.11 Describe how groups of elements
can be classified based on similar properties, including highly reactive metals*, less reactive metals, highly reactive nonmetals*,
less reactive nonmetals, and some almost completely nonreactive gases.
8.3.12 Explain that no matter how substances
within a closed system interact with one another, or how they combine or break apart, the total mass of the system remains
the same. Understand that the atomic theory explains the conservation of matter: if the number of atoms stays the same no
matter how they are rearranged, then their total mass stays the same.
8.3.13 Explain that energy cannot be
created or destroyed but only changed from one form into another.
8.3.14 Describe how heat* can be transferred
through materials by the collision of atoms, or across space by radiation*, or if the material is fluid, by convection* currents
that are set up in it that aid the transfer of heat.
8.3.15 Identify different forms of energy
that exist in nature.
* energy: what is needed to make things
* atom: the smallest particle of an element
that has the properties of that element
* element: the simplest type of pure
substance; a substance consisting entirely of atoms having identical chemical properties
* solid: matter with a definite shape
* liquid: matter with no definite shape
but with a definite volume
* gas: matter with no definite shape
* metals: one class of substances that
are mostly shiny, bendable, and good conductors of heat and electricity
* nonmetals: one class of substances
that does not have metallic properties; usually a poor conductor of heat and electricity
* heat: a form of energy characterized
by random motion at the molecular level
* radiation: energy transfer through
* convection: heat transfer in liquids
and gases by transport of matter from a region of one temperature to a region of a different temperature
Forces of Nature
8.3.16 Explain that every object exerts
gravitational force on every other object and that the force depends on how much mass the objects have and how far apart they
8.3.17 Explain that the sun’s
gravitational pull holds Earth and the other planets in their orbits, just as the planets’ gravitational pull keeps
their moons in orbit around them.
8.3.18 Investigate and explain that
electric currents and magnets can exert force on each other.
8.3.19 Investigate and compare series
and parallel circuits.
8.3.20 Compare the differences in power
consumption in different electrical devices.
The Living Environment
Students trace the flow of matter and energy through ecosystems*. They understand that the total amount of
matter remains constant and that almost all food energy has its origin in sunlight.
Diversity of Life
8.4.1 Differentiate between inherited
traits, such as hair color or flower color, and acquired skills, such as manners.
8.4.2 Describe that in some organisms,
such as yeast or bacteria, all genes* come from a single parent, while in those that have sexes, typically half of the genes
come from each parent.
8.4.3 Recognize and describe that new
varieties of cultivated plants, such as corn and apples, and domestic animals, such as dogs and horses, have resulted from
selective breeding for particular traits.
* ecosystem: a group of organisms in
an area that interact with one another, together with their nonliving environment
* gene: basic unit of heredity
Interdependence of Life and Evolution
8.4.4 Describe how matter is transferred
from one organism to another repeatedly and between organisms and their physical environment.
8.4.5 Explain that energy can be transferred
from one form to another in living things.
8.4.6 Describe how animals get their
energy from oxidizing their food and releasing some of this energy as heat.
8.4.7 Recognize and explain that small
genetic differences between parents and offspring can accumulate in successive generations so that descendants are very different
from their ancestors.
8.4.8 Describe how environmental conditions
affect the survival of individual organisms and how entire species may prosper in spite of the poor survivability or bad fortune
8.4.9 Recognize and describe that fossil
evidence is consistent with the idea that human beings evolved from earlier species*.
* species: a category of biological classification
that is comprised of organisms sufficiently and closely related as to be potentially able to mate with one another.
The Mathematical World
Students apply mathematics in scientific contexts. Students use mathematical ideas, such as symbols, geometrical
relationships, statistical relationships, and the use of key words and rules in logical reasoning, in the representation and
synthesis of data.
8.5.1 Understand and explain that a
number must be written with an appropriate number of significant figures (determined by the measurements from which the number
Shapes and Symbolic Relationships
8.5.2 Show that an equation containing
a variable may be true for just one value of the variable.
8.5.3 Demonstrate that mathematical
statements can be used to describe how one quantity changes when another changes.
8.5.4 Illustrate how graphs can show
a variety of possible relationships between two variables.
8.5.5 Illustrate that it takes two numbers
to locate a point on a map or any other two-dimensional surface.
Reasoning and Uncertainty
8.5.6 Explain that a single example
can never prove that something is always true, but it could prove that something is not always true.
8.5.7 Recognize and describe the danger
of making over-generalizations when inventing a general rule based on a few observations.
8.5.8 Explain how estimates can be based
on data from similar conditions in the past or on the assumption that all the possibilities are known.
8.5.9 Compare the mean*, median*, and
mode* of a data set.
8.5.10 Explain how the comparison of
data from two groups involves comparing both their middles and the spreads.
* mean: the average obtained by adding
the values and dividing by the number of values
* median: the value that divides a set
of data, written in order of size, into two equal parts
* mode: the most common value in a given
Students gain understanding of how the scientific enterprise operates through examples of historical events.
Through the study of these events, they understand that new ideas are limited by the context in which they are conceived,
are often rejected by the scientific establishment, sometimes spring from unexpected findings, and grow or transform slowly
through the contributions of many different investigators.
8.6.1 Understand and explain that Antoine
Lavoisier’s work was based on the idea that when materials react with each other, many changes can take place, but that
in every case the total amount of matter afterward is the same as before. Note that Lavoisier successfully tested the concept
of conservation of matter by conducting a series of experiments in which he carefully measured the masses of all the substances
involved in various chemical reactions, including the gases used and those given off.
8.6.2 Understand and describe that the
accidental discovery that minerals containing uranium darken photographic film, as light does, led to the discovery of radioactivity.
8.6.3 Understand that and describe how
in their laboratory in France, Marie Curie and her husband, Pierre Curie, isolated two new elements that were the source of
most of the radioactivity of uranium ore. Note that they named one radium because it gave off powerful invisible rays, and
the other polonium in honor of Madame Curie’s country of birth, Poland. Also note that Marie Curie was the first scientist
ever to win the Nobel Prize in two different fields, in physics, shared with her husband, and later in chemistry.
8.6.4 Describe how the discovery of
radioactivity as a source of Earth’s heat energy made it possible to understand how Earth can be several billion years
old and still have a hot interior.
Students analyze the parts and interactions of systems to understand internal and external relationships. They
investigate rates of change, cyclic changes, and changes that counterbalance one another. They use mental and physical models
to reflect upon and interpret the limitations of such models.
8.7.1 Explain that a system usually
has some properties that are different from those of its parts but appear because of the interaction of those parts.
8.7.2 Explain that even in some very
simple systems, it may not always be possible to predict accurately the result of changing some part or connection.
Models and Scale
8.7.3 Use technology
to assist in graphing and with simulations that compute and display results of changing factors in models.
8.7.4 Explain that as the complexity
of any system increases, gaining an understanding of it depends on summaries, such as averages and ranges*, and on descriptions
of typical examples of that system.
* range: the difference between the largest
and the smallest values
Constancy and Change
8.7.5 Observe and describe that a system
may stay the same because nothing is happening or because things are happening that counteract one another.
8.7.6 Recognize that and describe how
symmetry may determine properties of many objects, such as molecules, crystals, organisms, and designed structures.
8.7.7 Illustrate how things, such as
seasons or body temperature, occur in cycles.