The point where those electrons enter an electrical circuit is called the "source" of electrons. The point where the electrons leave an electrical circuit is called the "return" or "earth ground". The exit point is called the "return" because electrons always end up at the source when they complete the path of an electrical circuit.
Electric circuitry is a key component of the National Curriculum, particularly from ages 14, Key Stages 4 onwards. However this is a difficult concept to teach because it of its abstract nature.
This open hands-on model building effectively combines theoretical and practical STEM skills. Analogies are ideal in supporting and complementing this practical model making and reinforcing the principles taught.
It is difficult for students to understand how electric circuits function. The processes involved are invisible because they occur at the atomic level and thus are abstract in nature. Electricity can not be felt with using the personal senses (unless we receive an electric which is certainly unwanted), electricity cannot be manipulated directly, and what is happening is thus not readily apparent.