StoryMapJS is a free tool to help you tell stories on the web that highlight the locations of a series of events.
Here, we used it as a sort of timeline.
We wanted to show how two methods spread across Europe, over the ages, with two lines. One line for oral education, one for manual or bilingual education. Unfortunately, only one 'line' is allowed, so we used 2 different symbols. A mouth to indicate oral education, a hand to indicate manual or bilingual education.
You can find a second example, Deaf Monuments and Landmarks in Europe on the website of Deaf History: https://www.deafhistory.eu/index.php/monuments/deaf-monuments-map