The circuit breaker will open, or "break", the circuit when the current in that circuit becomes too high, or the fuse will "blow". This gives protection.
Resistors and other circuit elements can be connected in series or in parallel. Resistance in series circuits is the sum of the resistance.
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.
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.