The ballroom samba is danced to music in 2/4 time. The basic movements are counted either 1-2 or 1-a-2, and are danced with a slight bouncing action. This action is created through the bending and straightening of the knees, with bending occurring on the beats of 1 and 2, and the straightening occurring on the "a". Samba is notable for its constantly changing rhythms however, with cross-rhythms being a common feature. Thus, common step values (in beats are):