In the United States, two-way bilingual education eliminates the problems of subtractive bilingualism by

Teaching half the day in English and the other half of the day in the second language.

Explanation:

The term subtractive bilingualism could simply be described in a scenario where a student intends to learn a second language, such that this comes at expense of the student's first language. That is the student loses the ability to be good or better at his first language as a result of learning a second. In other to avoid this, the two way bilingual education concept is used to fix this issue by apportioning period for each Language lesson. Taking half a day on English and the other half in the second language of choice.

experiments.

surveys.

questionnaires.

interviews.

case studies.

participant and non-participant observation.

observational trials.

studies using the delphi method.