If you like this method of learning or of teaching, check out Oppia, open source software for building things like this: https://github.com/oppia/oppia
I'm not sure how socratease.in compares. But Oppia has some cool things like being able to set questions which require more than just multiple choice, e.g. requiring you to put a musical note in the right place on a stave.
The public site with existing lessons is here: https://www.oppia.org/library
I'm not sure how socratease.in compares. But Oppia has some cool things like being able to set questions which require more than just multiple choice, e.g. requiring you to put a musical note in the right place on a stave.