You will find the automatic saving functionality in the building tool under My loops as well as when editing a distributed loop.
In the building tool under My loops, the automatic save function is switched on all the time. But if you continue to build on a started loop, which your students are working in, you can choose to turn off the AutoSave function. If you turn off the function, everything works as before; you click the Save button to publish the changes so that your students can see them when you are done with a node.
In the video below you can see how it works.