Students don't really have a concept of writing the board. In fact, copy and paste is so prevalent that is there really a need to write on the board.
So, I would take writing your spelling words 20 times on the board, and I would change this activity - by having students write the spelling word on a web form. that after each word they would have to hit submit so that they could not copy and paste. Or perhaps I would find a way to block copy and paste. Its an old saying that repetition is the mother of all knowlege so my question is, how can you make sure that students really repeated? and did not just copy? without having the practice..
An interesting dilemma. It reminds me of page 6 in the book - where teachers are asked if they believe that students can learn while watching tv.. but really copying and pasting, while a new skill - does not get them to learn how to write the words properly.