Why does English Is the Medium of Instruction? Why not Dutch, French or What?

I assume you are referring to the Philippine educational system which requires that English language should be the principal medium of instruction from grade school to the tertiary level. There is a need to make English the principal medium of instruction in all schools because we have been losing our competitive edge in English proficiency to neighboring countries, including China, which used to abhor the English language. Even our graduates who are recruited by call centers have to be retrained so they will become fluent in English. To recall, English had been the medium of instruction until 1974 when the bilingual policy requiring the use of both English and Filipino was introduced. As a result of this policy, the learning of the English language suffered a setback. One reason is what linguists call language interference. Targeting the learning of two languages (English and Pilipino, actually Tagalog) is too much for Filipino learners, especially in lower grades. And if the child happens to be a non-Tagalog speaker, this actually means learning two foreign languages at the same time, an almost impossible task. The difficulty faced by the Filipino student in learning two languages at the same time could be one of the reasons why Filipinos lag behind their neighbors in science and mathematics. We know that that books in these disciplines are written in English. If the student cannot comprehend what is written in English, then learning science and mathematics and other disciplines becomes a tremendously difficult undertaking.