The Invisible Button is located just below the emergency button.
Recently I found a nice trick to welcome my students to my CLIL-art room. While standing at the doorway I make them pound the wall next to the entrance. “Do not forget to push The Invisible Button!” I have explained the meaning of this silly ritual to them: “It will remember you to change your mode from Dutch into English.”
In theory no Dutch word should be heard in my classroom. When addressing their teacher my students use English only, as they know that I will not even react to Dutch, if there is no life at stake. When they are communicating amongst each other I frequently catch them out at speaking Dutch though. It is a nuisance, and I lambaste them about it to no avail.