Toddlers rapidly develop hand and finger skills during their second year of life. They can now manipulate small objects with ease, turning the pages of books, building towers of blocks, and unzipping large zippers. Their newfound ability to coordinate their wrists, fingers, and palms allows them to screw and unscrew jars and lids, use a cup with one hand, turn a doorknob, or unwrap paper from a piece of candy. These new skills come with new challenges for adults to create a safe environment. Since children at this age can open bottles and jars with dangerous contents, adults must ensure harmful things are out of reach.
Shelov, S. P. (Editor-in-Chief). (2004.) Caring for Your Baby and Young Child: Birth to Age 5. The American Association of Pediatrics. Revised edition. New York: Bantam Books.