Teach your baby the sign for the word duck in baby sign language with the following description and video.
Form the hand into the signed letter H. Hold the hand in front of the mouth. Open and close the index and middle fingers and thumb to mimic the beak of a bird.
Beyer, Monica. 2006. Baby talk: A guide to using basic sign language to communicate with your baby. New York: Jeremy P. Tarcher/Penguin.