Recent and ongoing curriculum innovations in Dutch secondary chemistry education have led to questions about which concepts should be central in the programme and which contexts should be used to embed these concepts into. Another important question is in the discussions about these innovations is: how do students learn chemistry? This thesis examines the relations between students' metacognitive beliefs, their learning outcomes, and the learning activities they conduct in the domain of chemistry. In studying these relations, a useful framework is provided bij Novak's educational theory on 'meaningful learning' as is described in chapter 2. In chapter 3, the development of an instrument for assessing students' metacognitive beliefs regarding chemistry is described. More specifically, this instrument, a questionnaire, consists of items that can be used to determine the nature of students' epistemological beliefs, learning conceptions, and goal orientations concerning chemistry. Using this instrument, it was found that the students' aforementioned metacognitive beliefs were highly interrelated. By means of the data produced in this study, an improved version of the instrument was constructed. We used this version of the instrument in a follow-up study and identified a set of items to assess a student's 'competence mindedness'. 'Competence mindedness' is defined as the extent to which students are oriented towards coming to understand subject matter in the chemical domain. This orientation is for instance inferred from students' beliefs about chemistry as a coherent body of knowledge and about chemistry learning as a process in which knowledge is actively constructed. We describe a student's score on this scale as the extent to which he is oriented towards developing chemical competence, or, in short, the student's 'competence mindedness'. As an indicator of students' chemical competence we used the so-called 'macro-micro concept'. The macro-micro concept consists of the ability to use the macro perspective (focusing on chemical phenomena on a substance level) and micro perspective on chemistry (focusing on the structure and behavior of subatomic particles) interchangeably. Although the macro-micro concept is considered to be a central chemical competence by many experts in the field of chemistry education, the concept itself is not mentioned explicitely in any Dutch chemistry textbook used in secondary education. Using the final version of the instrument described in chapter 3, relations between the competence mindedness of students and a central chemical competency were assessed in chapter 4. Consequently, an explorative study was conducted in which a small number of chemistry teachers was questioned on the extent to which they paid attention to the macro-micro concept in their own teaching. Five out of nine teachers interviewed, held the opinion that the macro-micro concept should be a part of chemistry teaching and consequently dedicated time in class to this concept. The other teachers that were interviewed, did not mention the macro-micro concept as a central chemical concept in the interviews. In another study, students' use of the macro-micro concept when answering regular chemistry test questions, was examined. From this study, it can be concluded that there are large differences in the students' use of this concept. However, from answers given by the students involved, it can be concluded that they use the macro-micro concept.
Following from the last two studies mentioned, two more studies were conducted that focused on the use of the macro-micro concept by students. In particular we were interested in the way students use this concept differently than is to be expected from the sequencing of learning contents in chemistry textbooks. More specifically, we conducted two studies to determine if students' competence mindedness and the way they use the macro-micro concept (i.e. starting from the micro aspect or not) are related. In the first, small-scale, study, we concluded that senior students that are more competence minded, more often take the micro aspect of chemistry as a starting point when relating the micro and macro aspects of chemistry. In a follow-up study, a standardized instrument was used to assess students' use of the macro-micro concept. This instrument made it possible to include a larger sample of students in the study. This study confirmed the results found in the small-scale study: more competence minded students were found to prefer relations between the macro and micro aspects of chemistry that started from the micro aspect. Chapter 5 consists of several studies concerning students' notions about how the chemical domain can be described: their chemical domain beliefs. The development of these notions are considered an important indicator of chemical competence. Relations between students' competence mindedness and aspects of their chemical domain beliefs were examined through a repertory test procedure. More specifically, the students involved in this study were asked to compare the subject of chemistry with several other subjects. Thereby, data were gathered on constructs these students' used to describe the subject of chemistry and how they contrasted with the other subjects or resembled them. In another study, relations between students' chemical domain beliefs and the extent to which these students are competence minded were examined. The results show a number of relations between students' competence mindedness and selections of their chemical domain beliefs: in general, more competence minded students more often use concepts like 'chemistry as a science', 'properties of substances', and 'chemical reactions' to typify chemistry. Having found indications that students' competence mindedness regarding chemistry is related to their learning outcomes, the question arises how students' competence mindedness can be enhanced. Moreover, relations between students' competence mindedness and the learning strategies they deploy, have not been taken into consideration up to this point.
In chapter 6, a learning environment was redesigned in the form of a student study guide, that is used as a supplement to the chemistry textbook students were used working with. The main purpose of the study guide was to change the type of learning activities students use. The two quasi-experimental studies in which the study guide was used as an intervention, did not lead to significant changes in students' learning activities. However, relations were found between students' learning activities and the extent to which students were competence minded. We conclude therefore, that the learning strategies used by the students involved in the study are in particular a consequence of their metacognitive beliefs, i.e. their competence mindedness, and not of the learning environment concerned.