Abstract: An educational toy comprising support means arranged or arrangeable to define a plurality of adjacent stations, a supply of elements each bearing at least one character from which elements the solution of a problem represented by the stations can be built up by placement of the elements on respective stations, and co-operating means on the stations and elements, for verifying that a correct element is mounted on any station, characterized in that the supply of elements is divided into a plurality of groups each having a distinctive visible coding and the stations each bear the appropriate group coding, so that an appropriate element can be chosen from a predetermined number of possibilities corresponding to the number of different elements in its group. The support means can consist of a board marked with a device showing the problem and associated means for receiving the elements, and constituting the stations. Alternatively, the support means can consist of reference elements, cryptically marked e.g.