This takes too much time and is relevant only for making line graphs, which finally does not happen. Remove.

(it takes most students more than 40 min because they are not acustommed to JavaScript – which is perfectly OK)

This section is apparently not clear enough. (I got several questions about event triggering)

Use UML sequence diagrams ? (maybe, maybe not)

This section is especially poorly introduced. Students don't get what "dispatch" is.

This exemple is actually probably too complicated to focus only on events. Maybe just texts should be better. The positioning of the circles is just too distracting.