from the American Association for the
Advancement of Science:
Benchmarks for Science Literacy
- All matter is made up of atoms, which are far too
small to see directly through a microscope. The atoms of any
element are alike but are different from atoms of other
elements. Atoms may stick together in well-defined
molecules or may be packed together in large arrays. Different
arrangements of atoms into groups compose all substances.
- Atoms and molecules are perpetually in
- There are groups of elements that have similar
properties, including highly reactive metals, less-reactive metals,
highly reactive nonmetals) such as chlorine, fluorine, and oxygen),
and some almost completely non-reactive gases (such as helium and
- No matter how substances within a closed system
interact with one another, or how they combine or break apart, the
total weight of the system remains the same. The idea of atoms
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.
- Models are often used to think about processes
that happen too slowly, too quickly, or on too small a scale to
observe directly, or that are too vast to be changed deliberately, or
that are potentially dangerous.
- Different models can be used to represent the
same thing. What kind of a model to use and how complex it
should be depends on its purpose. The usefulness of a model may
be limited if it is too simple or if it is needlessly
complicated. Choosing a useful model is one of the instances in
which intuition and creativity come into play in science, mathematics,
- Elements are arranged on the periodic table based
on the number and location of their subatomic particles.
- Elements are arranged on the periodic table
according to increasing atomic number.
- Elements behave differently based on the location
of their subatomic particles.
- Elements in the same family exhibit similar
- The periodic table is based on the premise of
periodicity (i.e. repeating patterns).
- Scientists differ greatly in what phenomena they
study and how they go about their work. Although there is no fixed set
of steps that all scientists follow, scientific investigations usually
involve the collection of relevant evidence, the use of logical
reasoning, and the application of imagination in devising hypotheses
and explanations to make sense of the collected evidence.
- If more than one variable changes at the same
time in an experiment, the outcome of the experiment may not be
clearly attributable to any one of the variables. It may not always be
possible to prevent outside variables from influencing the outcome of
an investigation (or even to identify all of the variables), but
collaboration among investigators can often lead to research designs
that are able to deal with such situations.
- What people expect to observe often affects what
they actually do observe. Strong beliefs about what should happen in
particular circumstances can prevent them from detecting other
results. Scientists know about this danger to objectivity and take
steps to try and avoid it when designing investigations and examining
data. One safeguard is to have different investigators conduct
independent studies of the same questions.
- New ideas in science sometimes spring from
unexpected findings, and they usually lead to new investigations.