"The most common implementation of RTI is fairly rigid,"

she said, with schools often using a single test to identify students for Tier 2 and a standard set of interventions once they get there. For example, she noted that the study found that small group instruction and interventions in RTI schools were more likely to focus on phonics for students below grade level than at grade level. "Right there you have a clue that the interventions are focused on these foundational skills and not as much on comprehension," she sai