The achievement gap theories in education

We believe that all students can learn, but the extent of their learning is determined by their innate ability or aptitude. This aptitude is relatively fixed, and as teachers we have little influence over the extent of student learning. It is our job to create multiple programs or tracks that address the different abilities of students, and then guide students to the appropriate program. This ensures that students have access to the proper curriculum and an optimum opportunity to master material appropriate to their ability.

What would be a justification for this position? It is alluding to a secondary education setting.