Cooperative learning in practice is one of just many strategies that embrace social learning theories - the idea that people learn best when engaged in discourse with others. Cooperative learning can be used in a variety of ways in the classroom. Pair-shares are a quick means of having two students dialogue about the content and check each other for understanding. Groups of 3 works much in the same manner but can be utilized for making predictions, responding to prompts, or the like. Jigsaws are a personal favorite of mine. Students are members of not one but two groups (the original group and a sub-group) where they become the expert on the subject matter "teaching" their original group about the research they conducted. The teacher's role becomes that of facilitator as opposed to the expert dispensing information. Students can be placed in groups according to abilities, interests, diversity, or age.
Technology supports this type of learning. Skype, blogs, wikis, GoogleDocs, Facebook and the like are all geared toward the sharing of information and understandings. These technologies link students together in a way that is not possible in a traditional classroom. Groups can research and post their findings with the assurance that all members have access immediately to the same information. Edits and additions can be collaboratively agreed upon and made by any group member.
One exciting technology that is utilizing social learning theories in particular is VoiceThreads. An individual or group can compose a VoiceThread on any topic of their choosing. Then, once posted and shared, it is available for comment by anyone, anywhere with an internet connection. I tried my hand at creating a problem-based VoiceThread on the Battle of Gettysberg. Here is the URL to view and comment on it: http://voicethread.com/share/2906316/