164 SUMMARY 112. Science will be the major domain in PISA 2015 and the 2015 definition builds on and
develops the 2006 definition. In particular, the competencies required for scientific literacy have
been further elaborated and the concept of ‘knowledge about science’ has been defined as two
forms of knowledge
– procedural and epistemic. In addition, the 2015 framework has articulated a
conception of the range of cognitive demand required of items. The 2015 framework therefore
represents a more detailed specification of particular aspects of scientific literacy that were
embedded or assumed in the earlier definitions.
113. The PISA 2006 definition of scientific literacy has its origin in the consideration of what 15-
year-old students should know, value and be able to
do as “preparedness for life” in modern
society. Central to the definition and the assessment of scientific literacy are the competencies that
are characteristic of science and scientific enquiry. The ability of students to make use of these
competencies depends on their scientific knowledge, both their content knowledge of the natural
world and their procedural and epistemic knowledge. In addition, it depends on a willingness to
engage with science related topics. Their attitudes towards science-related issues are measured
separately in the background questionnaire.
114. This framework describes and illustrates the scientific competencies and knowledge that will
be assessed in PISA 2015 (see Figure 28), and the contexts for test items. Test items will be
grouped into units with each unit beginning with stimulus material that establishes the context for
items. A combination of item types will be used. Computer-based delivery for 2015 offers the
opportunity for several novel item formats, including animations and interactive simulations. This
will improve the validity of the test and the ease of scoring.