We report on the advantage of integrating teaching of biology and physics in the 7th grade as compared to the teaching physics and biology as discrete units. Experimental group (EG) had a lesson integrating knowledge of physics and biology, while control group (CG) had discrete lessons in physics and biology, referring each to their specific topics. The competence of the EG and CG in finding connections between the physical and biological phenomena has been measured by the use of school standard scoring system. The study was aimed at finding out if integrated teaching of biology and physics helps 7th grade pupils in better understanding of interconnections between biological and physical phenomena as compared to the teaching of physics and biology as discrete units. The topic under discussion was an adaptation of birds to fly and the action of lifting forces. At the integrated lesson EG observed the shape of a bird wing and tested the model of a wing in motion. At the same time, EG conducted physics experiments, demonstrating the action of lifting forces. CG was engaged in the same activity. However, CG observed the shape of a wing and tested the model of a wing at biology lesson, while experiments on lifting forces have been conducted at a lesson of physics. Both groups were requested to write one page assay to explain in details the interaction of lifting forces and wing shape during fly. Answers were assessed by standard school scoring system. Statistically reliable difference in the scores between the EG and CG has been revealed. EG displayed better understanding of the bird fly and predominated over the CG in the precise interpretation of connections between the shape of a wing and the action of lifting forces. Presumably, integrated teaching of physics and biology in the 7th grade helps pupils in better understanding of interconnections between physical forces and structure and function of living things as compared to the teaching of physics and biology as a discrete units.