Final answer:
The text's central idea is that modern off-reservation boarding schools for Native American teenagers no longer coerce assimilation, but still fail to actively foster cultural expression and reconnection. Historically, these schools played a significant role in forced assimilation and eventual policy reforms have led to some improvements.
Step-by-step explanation:
The central idea of the text best identified is that while off-reservation boarding schools may no longer actively force assimilation into American culture upon Native American students, they also do not actively promote or encourage these students to express and reconnect with their cultures. Historically, such schools were an instrument of cultural erasure and assimilation into Euro-American ways of life. Multiple iterations of these schools have existed, from forcefully removing children to adopt English and Christianity to the efforts of instating reforms that address health and vocational training. The progression towards autonomy from assimilation and the acknowledgment of Native Americans' rights has been a significant yet slow historical shift.
Throughout history, Native American culture was eroded via forced assimilation policies embedded in the education system of boarding schools. Practices in such schools, including stripping children of their cultural identifiers and enforcing English, aimed to integrate Native youth into White culture. It wasn't until later reforms, such as the Indian Religious Freedom Act and the Native American Graves Protection and Repatriation Act, that steps were taken to undo some of the broader assimilation policies.