Handwriting notes is an effective strategy for knowledge retention because writing is a cognitive process. It is one of the strategies of active learning because it engages the brain to maximize understanding and retention. Eschewing high tech methods of note-taking(e.g. laptops, tablets, etc.)  in favor of low tech handwritten notes has cognitive benefits. Brain imaging shows that low-tech writing by hand increases neural activity in certain sections of the brain. Studies have demonstrated that putting pen or pencil to paper is more beneficial than using a keyboard for retention.

Ironically, the speed of typing can actually prove detrimental for effective note-taking. Typing usually exceeds handwritten notes, often resulting in transcription. Laptops  . . . may be impairing learning because their use results in shallower processing. . . Students who took notes on laptops performed worse on conceptual questions than students who took notes longhand.  However, the slower hand movements involved in writing allow the note-taker to include the most important ideas from a lecture or text.  Writing  allows the learner to make connections between idea units and engage in deep processing of course content.   In fact, some educational research goes so far as to recommend cursive note taking over printed notes.  Studies have found that it activates different neurological pathways than typing or manuscript writing.  

Hand-written note-taking techniques generally fall into two categories: linear and non-linear. Linear notes are sequential, while non-linear notes usually do not start at the top of a page and proceed from there. They  involve the use of graphics like matrices, mind-maps, clustering, concept mapping, Cornell Notes, and idea mapping.  The learner can select the technique that most appeals to him.

Yet, taking notes in class is only the first step in the active learning process. After the initial note-taking, the learner should reduce those notes summarizing them, including only key concepts. The more a learner revisits the notes, the more opportunity he has to further re-write and reduce them. Before taking new notes, the learner should also review previous notes, as repetition is key to memory retention. 

So, to engage in active learning, close the laptop and get out the pen and paper!