How were reservations supposed to “Americanize" the Plains tribes?

Indoctrinating the children

Schools often forced the pupils to dress like eastern Americans. They were given shorter haircuts. Even the core of individual identity  one's name was changed to "AMERICANIZE" the children. These practices often led to further tribal divisions. Each tribe had those who were friendly to American "assistance" and those who were hostile. Friends were turned into enemies.

Explanation:

The Dawes Act was an unmitigated disaster for tribal units. In 1900, land held by Native American tribes was half that of 1880. Land holdings continued to dwindle in the early 20th century. When the Dawes Act was repealed in 1934,, poverty,  were higher for Native Americans than any other ethnic group in the United States. As America grew to the status of a world power, the first Americans were reduced to hopelessness.

it is a because im a fod nigba

worcester v. georgia, legal case in which the u.s. supreme court on march 3, 1832, held (5–1) that the states did not have the right to impose regulations on native american land. andrew jackson refused to enforce the ruling, the decision form the basis for most subsequent indian law in the united states.