Secondary-level students need a profound understanding of food relationships to assess the impact of human interventions on ecosystems. Food relationships are often introduced via food webs in early secondary education; however, current research shows that describing changes in food webs is challenging for students and that they tend to focus on individual organisms rather than populations. This study with German 6th graders (N = 28) investigated how an age-appropriate population concept, introduced through two consecutive text stimuli, can serve as a stepping stone to more sophisticated descriptions of (in-)direct effects and population dynamics in food webs. The students were interviewed before, in between and after reading the stimuli. Qualitative content analysis and frequency analyses were employed to examine the development of their descriptions of food web interactions during the interview. Our results indicate that shifting students’ perspectives from individual organisms to populations, especially regarding carnivore predators, was crucial in fostering more scientifically adequate descriptions of indirect effects and fluctuating predator-and-prey populations in food webs; consequently, we recommend employing an agent-based perspective that conceptualises individuals as members of groups.