Georg Greger patented the Lectron System in May of 1965 with the descriptor ‘Elektronikbaukasten‘ (electronic construction kit or electronic building blocks. In English, the Lectron System was often called ‘Electronic Dominoes‘). It was introduced to the public in 1966.
The Lectron System was considered a unique and highly inventive way of teaching analog and digital electronics.
Using transparent plastic blocks with magnets behind small metal conductive plates that could be put together to form an electrical connection with the magnets holding the blocks together. Different electronic components (resistors, capacitors, transistors, photo cells, pots, et cetera) would be soldered within a particular block. A white plastic cover with the appropriate electrical symbol would be placed on top identifying the component inside. Putting the blocks together in the right way would form a functioning circuit or device with the white covers displaying an accurate schematic diagram.
53 years later (as of 2019), the Lectron System remains the most versatile, comprehensive and functional pedagogical platform to illustrate the electrical nature of chemistry, biology, and of course electronics concepts.