Final answer:
A proportion of students require Tier 2 or Tier 3 instruction despite effective Tier 1 instruction, typically around 15-20% for Tier 2 and 5% for Tier 3. Structural issues like teacher qualifications and equitable resource allocation affect these needs.
Step-by-step explanation:
The question relates to the effectiveness of differentiated instruction tiers within educational settings, particularly Tier 1 (general instruction), Tier 2 (targeted interventions), and Tier 3 (intensive interventions). When Tier 1 instruction is effective, there is still a proportion of students who require additional support through Tier 2 or Tier 3 instruction. Although the question does not specify an exact percentage, research and practice suggest that 15-20% of students may require Tier 2 supports and approximately 5% may need Tier 3 intervention. These percentage ranges can vary depending on the effectiveness of Tier 1 instruction and the specific needs of a student population.
Moreover, there are structural issues in education, such as underqualified teachers, that can exacerbate the need for higher tiered interventions. In the United States, there is a disparity in the specialization of teachers in their subject areas, especially in disadvantaged schools. Increased financial resources alone have not solved the complex challenges in education, indicating that structural reforms are also crucial.