From an article in The Atlantic:
"...this might be the key to their findings: Take notes by hand, and you have to process information as well as write it down. That initial selectivity leads to long-term comprehension."
Secondly getting the active participation of students is more effective than long lectures. No surprise really, the trick is how... the article does give some clues. One more thing - putting the lecture on a computer does not improve learning. From the article in Science :
"A new study finds that undergraduate students in classes with traditional stand-and-deliver lectures are 1.5 times more likely to fail than students in classes that use more stimulating, so-called active learning methods."