If you are a parent and your kids are among the batches of students studying Math and Science in English, I suggest you take my advice seriously.
Most students particularly non-Malays who spend limited hours learning in Bahasa Melayu, are seeing their standard dropping drastically compared to students before the implementation. My observations are based on the writing skills of urban kids in areas such as Petaling Jaya and Subang Jaya. The standard of Bahasa Melayu for primary level is in fact more critical than the secondary level (because students in secondary level gained more exposure when they were in primary level).
Many parents and students might not take this seriously and think that Bahasa Melayu is not an important subject. But let's not forget that Bahasa Melayu is a compulsory subject in the SPM level. It is useless if you get As in other compulsory subjects and elective papers but do not pass in Bahasa Melayu.
I urge students especially the non-Malays to start looking for tutors to improve their writing and reading skills in Bahasa Melayu. Or at least start reading Utusan or Berita Harian to enhance their language ability.