Ever since Long (1983) concluded that instruction makes a different in Second Language Acquisition (SLA), many researchers have attempted to examine the effectiveness of various kinds of instruction in L2 classrooms (e.g. Farley, 2005; Wong, 2004). In fact, last two decades have experienced an evolution in classroom research and more studies (Benati,2001; Doughty & Williams, 1998) have attempted to investigate the appropriate method of implementing instructional treatments in the classroom. Within this paradigm of research, one important problem is whether providing instruction through one modality (input-based or output-based) is more effective than others.