Energy is an important concept in all natural sciences, and a challenging one for school science education. Students' conceptual knowledge of energy is often low, and they entertain misconceptions. Educational research in science and mathematics suggests that learning through depictive representations and learning from errors, based on the theory of negative knowledge, can potentially foster students' knowledge of abstract concepts such as energy. Thus, we propose here an instructional approach that combines these two strategies to foster conceptual knowledge of energy. It involves inserting an error in a biological energy flow diagram, an error that we derived from two prevalent misconceptions about energy: 1) plants get some of their energy from the soil or 2) energy cycles in an ecosystem. The approach's effect on students' conceptual knowledge of energy was tested in an intervention study with pre-post design and 304 ninth grade students (M = 14.79 years). Students who successfully identified and explained the error achieved larger gains in conceptual knowledge than students learning with a correct diagram. Thus, the proposed instructional approach holds promise for improving energy teaching.