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44. The three competencies required for scientific literacy require three forms of knowledge that
are discussed below.
Content Knowledge
45. Only a
sample
of the content domain of science can be assessed in the PISA 2015 scientific
literacy assessment. Hence, it is important that clear criteria are used to guide the selection of
knowledge that is assessed. These are that knowledge to be assessed will be selected from the
major fields of physics, chemistry, biology, earth and space sciences such that the knowledge:
has relevance
to real-life situations;
represents an important scientific concept or major explanatory theory that has enduring
utility;
is appropriate to the developmental level of 15-year-olds.
46. Therefore it will be assumed that students have some knowledge and understanding of the
major explanatory ideas and theories of science such as our understanding of the history and
scale
of the Universe, the particle model of matter, and the theory of evolution by natural selection.
These examples of major explanatory ideas are provided for illustrative purposes and there has
been no attempt to list comprehensively all the ideas and theories that might be seen to be
fundamental for a scientifically literate individual.
47. Figure 4 shows the content knowledge categories and examples selected by applying these
criteria. Such knowledge is required for understanding the natural world and for making sense of
experiences
in personal, local, national, and global contexts. The framework uses the term
“systems” instead of “sciences” in the descriptors of the content knowledge. The intention is to
convey the idea that citizens have to understand concepts from the physical and life sciences,
earth and
space sciences, and their application in contexts where the elements of knowledge are
interdependent or interdisciplinary. Things viewed as subsystems at one scale may themselves be
viewed as whole systems at a smaller scale. For example, the circulatory system can be seen as
an entity in itself or as a subsystem of the human body; a molecule can be studied as a stable
configuration of atoms but also as a subsystem of a cell or a gas. Hence, applying scientific
knowledge and deploying scientific competencies requires consideration of which
system and
which boundaries apply to any particular context.