Constructionist learning is inspired by the constructivist theory that individual learners construct mental models to understand the world around them. However, constructionism holds that learning can happen most effectively when people are also active in making tangible objects in the real world. In this sense, constructionism is connected with experiential learning, and builds on Jean Piaget's epistemological theory of constructivism.
Seymour Papert defined constructionism in a proposal to the National Science Foundation entitled Constructionism: A New Opportunity for Elementary Science Education as follows: "The word constructionism is a mnemonic for two aspects of the theory of science education underlying this project. From constructivist theories of psychology we take a view of learning as a reconstruction rather than as a transmission of knowledge. Then we extend the idea of manipulative materials to the idea that learning is most effective when part of an activity the learner experiences as constructing a meaningful product."
In Moodle, the term "context" may have a specific meaning.
A Moodle context is a place where permissions are assigned to a user (usually through a role). In Moodle, contexts are layered in a hierachry. Some examples: a site is the overall context; each course category is a context in the site; each course is a context in it's course category; each topic/section is a context and the resources and activities in a topic/section are contexts. Blocks, filters and special pages are contexts that are at minimum part of the site context. Permissions are passed down automatically. For example, a user who has a teacher role in a course will be assigned that role when a Forum context is created. Roles for individuals or groups can be changed in a context. This makes it possible for one user to be a teacher in one context and a student in another.
Cron is an Automatic sytem in moodle that sends out messages to the system through.
For more information on Cron check the moodle docs page and your help section in moodle.