The term for placing students in homogeneous groups according to intellectual ability is:

The term for placing students in homogeneous groups according to intellectual ability is Tracking. Tracking, also known as ability grouping, involves separating students into different classes or educational pathways based on their perceived academic capabilities or achievement levels. These groups are typically homogeneous, meaning students within a track share similar intellectual abilities, which often leads to differentiated curricula and pacing.

• Inclusion is incorrect because it is the practice of educating students with disabilities in general education classrooms alongside their non-disabled peers, emphasizing integration and diversity, not separation by ability.
• Mainstreaming is incorrect; it was a precursor to inclusion, where students with disabilities spent part of their day in general education classes, but it doesn't describe homogeneous grouping by intellectual ability.
• Individualized instruction is incorrect as it refers to tailoring teaching methods and content to meet the unique needs of each student, which is a pedagogical approach rather than a student grouping method.