The example of Hong Kong may be instructive here: As of this September, Cantonese has replaced English as the language of education in Hong Kong middle schools. But some say that due to differences in meaning between words in Cantonese--a spoken, not written, dialect--and the standard Chinese characters used to write them, some ideas have become "muddled" in the texts.
香港中學的教學語言在今年九月從英語回歸到廣東話，也有人認為口語的廣東話跟書寫的中文有距離，會有「表達不清楚」的問題。