**3. Teachers' integrative knowledge**

Lee Shulman has described the development of teacher education as a process in which pedagogical knowledge has become more and more openly acknowledged as essential competence along with subject matter content knowledge. However, according to Shulman, not enough attention has been given to the pedagogical skills necessary for teaching certain subject contents. Shulman's point is that pedagogical knowledge has been seen as too general, applicable to teaching any subject and all content. Instead, Shulman stresses the importance of pedagogical knowledge with which teachers can teach specific content in different subjects. The content of every subject needs its own pedagogical approach, i.e., *pedagogical content knowledge* to make it comprehensible to students. This is what Shulman has called *the missing paradigm* [2], although it has been argued that the paradigm has not been entirely missing, because it has long been a central feature of the German tradition of subject didactics (*Fachdidaktik*) [18].

Shulman presented his argument three decades ago, and the tradition of didactics has a much longer history. In Shulman's theory and in the tradition of subject didactics, the pedagogical questions of school subjects have been widely discussed, but pedagogies of CI have been taken up to a much lesser degree. Additionally, the recent discussion on development of teacher's competences has been bind to subject teaching [19]. This can be called *the missing paradigm of today*. There are many manuals of CI and reports of experiments on CI, but the question of what kind of pedagogical knowledge CI requires from teachers is rarely answered. Generally, researchers have been more interested in well-working performance than in the knowledge base and reasoning of teachers [20].

As Kansanen [18] states, Shulman's model fits research purposes well, and the tradition of didactics acts more as a normative basis for teachers in their work. Although Shulman has been criticized for a static understanding of the meaning of subject matter [16], there are many reasons why in this chapter Shulman's theory is applied to the study of the challenges of CI. First, Shulman's theory of teachers' knowledge serves as a clear model for analyzing the requirements of teachers' work. Second, Shulman is open to the idea of CI, although he does not examine it from the viewpoint of teachers' knowledge. In any case, Shulman sees CI as one possible way of constructing a curriculum. However, he claims that if CI is taken seriously, it will have profound consequences when the discussion of how a scientific discipline becomes a school subject changes to something else [21], because if a curriculum is integrated, then there are no longer subjects with parallel disciplines. Finally, his examples come mostly from secondary schools. This suits the level of interest in this chapter.

The strategy in this chapter is to examine the effects of CI on different categories of teachers' knowledge. We discuss four Shulman's categories that are most relevant from the viewpoint of CI: (1) content knowledge, (2) curriculum knowledge, (3) pedagogical content knowledge, and (4) knowledge of educational ends, purposes, and values. Shulman presented interdisciplinarity as a part of content and curriculum knowledge [22]. He has not explained all these knowledge categories at length and has used them in an inconsistent way in different texts [23]. For those reasons, some of categories are seen to be partly overlapping [24].

In this section, another category is added as the aforementioned knowledge categories are interpreted and discussed from the perspective of CI. This category can be called *integrative pedagogical knowledge*, which crosses all categories. It is not an independent knowledge category, but an approach to each category from the perspective of CI. It is an addition to Shulman's subject-centered theory. The following sections describe what kinds of integrative pedagogical knowledge teachers need in order to implement CI. In short, teachers need understanding of CI as one option for constructing a curriculum, and they need broad knowledge of the current curriculum, including the content and objectives of subjects they are not teaching themselves. For CI to be successful, its purpose has to be clearly comprehended. Furthermore, in collaborative forms of CI, teachers need good skills and conditions for cooperation across subject borders.
