Tips for Beginners: Building an electrical device for use in teaching logic

In a mathematics course designed for prospective teachers at the University of Illinois, the students were required to design and build a project that could be used in a high-school classroom to illustrate or demonstrate some mathematical concept. Since earlier in the semester we had discussed the growing emphasis that is being given in high schools to the study of symbolic logic, I decided to build an electrical device that would graphically represent the truth table and the various operations which can be performed on propositions.