All but which of the following cautions have been raised about using RTI as a means of identifying students with learning disabilities? RTI often fails to identify students in the early elementary grades. There is little large-scale research about the effectiveness of using RTI as a model for identification. Most of what we know about RTI focuses on reading. Some students are caught in a cycle where they respond well to Tier 2 instruction, are returned to Tier 1, and then are referred back to Tier 2.