Issue Summer: http://archive-edutice.ccsd.cnrs.fr/edutice-00000835 software distributed under the lock title can be seen from two points of view: result of a programming activity offered to pupils or starting point of a new activity that should lead to a graphical screen simulation of the operation of a schematic lock. In the course of our presentation, we will focus on this second point of view by first offering basic software that we have designed on the basis of criticism of existing versions and then programming activities using that software. These activities are aimed in particular at students in the Middle Course both in terms of intellectual skills and the knowledge they require or help to develop; the aim is to “have pupils programmed from a logistical perspective”, i.e. to give them “a fair idea of the concept of organised and automated calculation carried out on a set of data themselves organised and producing the desired effects”. We refer here to the supplements to the programmes and instructions of the elementary school, a text which refers at length to the subject of the lock and which we will have several times to mention.