The focus of this study was to portray the ideas that students with four years experience in learning physics developed in regard to the second law of thermodynamics. Data were obtained through 34 clinical interviews with grade 10 students. An analysis of student arguments revealed deeply rooted difficulties in using concepts that were learned in school. There appears to be a strong tendency for students to rely on everyday knowledge rather than knowledge obtained in class. Moreover, the second law of thermodynamics as a topic of science instruction has been almost totally neglected, especially in the lower grades. Most students, therefore, do not learn a law that provides a very deep insight into the way nature works. A basic understanding of the principle of energy conservation requires a basic understanding of the principle of energy degradation. Results of this study indicated that basic aspects of the second law of thermodynamics are not too difficult to be learned in the lower grades, but that such learning will only be possible when students are provided with a sound conceputal framework in the areas of heat, temperature, energy, and the particle model. (Author/CW)