Teaching your pup to close the curtain can be both fun and useful. After all, wouldn't it be nice to just be able to ask your puppy to close the curtain for you instead of having to get up when you are comfortably situated on the couch trying to wind down after a long day?
If your puppy tends to be destructive in your home and tear things up, then you might want to wait to teach him this until he is past the chewing phase and no longer tends to destroy things.
Once you have taught your puppy this trick, if he starts to close the curtains on his own when you have not asked him to, then do not reward him for it. Only reward him for closing the curtains when you tell him to in order to avoid all of your curtains being constantly closed when you do not want them to be!