I'm pleased to announce that from now on a new "Revise" button will be appearing on lessons:
Previously, when a lesson was due for revision, the green "Learn" button re-appeared. This was a little confusing, since you had already gone through the "Learn" phase. Now it was simply revision. It almost seemed sometimes that you were making no progress. Now it should be much clearer that you are revising, rather than just learning from scratch again. Although the changes is quite subtle, I think it will be important to keep you motivated in your learning.
The Revise button will not appear immediately for all your existing lessons due for revision, but will gradually appear as they become due for revision in the future.