Here is a transcribed article from the September 1967 issue of Electronics Illustrated describing what is, in fact, the BRAUN Lectron educational toy designed by Dieter Rams and Jurgen Greubel. Interestingly, the toy’s U.S. marketing, at the time, seems to have been pretty thoroughly scrubbed of conspicuously German names. The article mentions that the system was “imported from Germany,” but neither Braun’s, Rams’s, nor Greubel’s name is given, and U.S. distributor Raytheon gets most of the credit. That aside, there’s a solid technical description of how the toy works:

Instead of using clips, binding posts, or springs to hold parts together, each box is equipped with small magnets at the points where it is to contact another box or the board. The sides and the bottom of each box are made of clear plastic so you can see what’s inside. The top of each box – carrying the schematic symbol – is opaque white.

Some of the circuits can, incidentally, be a little touchy. Squeeze a little here, apply some pressure there and suddenly the circuit works like a charm – a light blinks, the meter needle moves or the speaker sounds. The longer we used the set, however, the less we seemed to have contact problems.