Tree abstraction of learning-content schema

learning-content-schema.js

[
    {
      id: 'class-1',
      subjects: [
        {
          id: 'subject-1-class-1',
          modules: [
            {
              id: 'module-1-subject-1-class-1',
              ...
            },
            ...//other modules go here
          ]
        },
        ...//other subjects go here
      ]
    },
    ...//other classes go here
  ]