ABSTRACT. Knowledge structure is an important aspect for defining students’ competency
in biology learning, but how knowledge structure is influenced by the teaching process in
naturalistic biology classroom settings has scarcely been empirically investigated. In this
study, 49 biology lessons in the teaching unit blood and circulatory system in 9th grade
German classrooms were videotaped and analyzed. Before the lesson, a questionnaire was
administered to the students to solicit their responses about learning motivation. After the
lesson, students’ learning outcomes on knowledge structure were examined with the concept
mapping method. The video coding used in this study focused on the knowledge linking levels
during the biology lesson. Out of the 49 classes, those with the highest and those with the
lowest linking levels were selected based on the coding results. In high-linking classes,
interrelated facts were introduced more often in the lessons, whereas in the lessons of the lowlinking
classes, isolated pieces of knowledge were predominant. The results from the concept
mapping task showed that the students in the high-linking classes constructed more correct
relations among the concepts compared to the students in the low-linking classes. The results
remained stable even after controlling for learning motivation. These findings confirm the
importance of teaching interrelated facts and concepts instead of isolated facts for fostering
students’ knowledge structure. As a result, based on the Bavarian biology curriculum, we
develop materials and programs to enable students, student teachers, and teachers to focus on
interrelated facts and basic concepts instead of isolated facts in biology lessons.