The interference of everyday and scientific languages constitutes a very essential cognitive obstacle. This phenomenon has been studied quite well as far as concepts from mechanics, the science of heat, and optics are concerned. The problem is closely connected with the so-called everyday knowledge of pupils. The situation in mechanics and the science of heat is particularly drastic here. Words such as: force, power, work, energetic, powerful, strong, not only have a fairly broad and not well-defined everyday meaning but that meaning is plainly in contradiction with their physical definition.
In spite of all appearances, this is not an easy problem to solve. It is impossible to use precise scientific language from the start on. Some definitions are too difficult to be introduced explicite right at the beginning, they have to be introduced step by step. Furthermore, and this is perhaps more important, we have to communicate with children using a language that is understood by them, i.e. the language of everyday life. The careful teacher, should stress scrupulously in each such case that "we say this in everyday life", and then rephrase it using the correct language of physics. This is the same as teaching a new language through context. One can hope that the precise language of physics will make the everyday language more accurate.