This type fracture is characterized by a partial break on one side of the bone (compression force), with bending on the other side (tension force).  A greenstick fracture only occurs in children because their bones have yet to fully ossify.  This is an x-ray of the forearm of an eight year old boy.  The distal ends of both the radius and ulna are fractured.


Photo courtesy of Green and Swiontkowski, p. 198