I was taught to use two spaces.   Apparently there was a reformation of the the double space rule sometime thereafter.    I would expect to be informed about such an important change in English grammar through a high exposure world-wide public announcement campaign. Considering that the use of double spaces separating sentences can provoke such ridicule, there really needs to be a global effort to educate all English speaking citizens of Earth.     Perhaps even training centers could be erected where people could be taught this new important change to the language.       These centers could perhaps even treat those who have been subject to the extreme psychological trauma of the public ridicule caused by the misuse of the space.