If you have seen tubes like the ones we describe here in the back of a cupboard but have been reluctant to use them, now is the time to get them out. The aim of this article is to record the history of teaching about electron beams, particularly with Teltron equipment, and in doing so encourage those schools that are equipped with these tubes to make more use of them. There will of course be many teachers who know the tubes well but this article is for those who do not. (Contains 1 footnote, 1 table, and 6 figures.)