Social constructivism is closely related to Social constructionism in the sense that people are working together to construct artifacts. However, there is an important difference.
Social constructionism focuses on the artifacts that are created through the social interactions of a group (Wikipedia is a good example of social constructionism at work), while
social constructivism focuses on an individual's learning that takes place because of their interactions in a group.
http://www.funderstanding.com/content/constructivism
There are many videos on this topic available via Youtube.
Here is one that is a bit rappy.