Technical subjects are very often part of vocational curricula. For professional planning there exist different planning strategies (UML, flowcharts,...). My favourite online tool is www.diagramm.ly. After discussing your eTwinning activities with your students you can draw you project plans with it.
Note for technicians - you will find a great and free UML-online tool here:
Tricider is a social voting tool. The creation of questions is very easy (no registration required). Students are able to add answers and to vote.
https://www.youtube.com/watch?feature=player_embedded&v=dvLuwL9Quzw