Studying in an international school setting offers an excellent opportunity for students to acquire the target language, English, through abundant language exposure. As observed during classroom observations, several students outperformed their peers in targeted language production despite the same school language exposure. Extramural English is assumed to play a substantial influence. This case study explored the Extramural English exposure of 15 ninth-grade students, the duration of such exposure, and the language accuracy of their academic writing captured after receiving it. A qualitative design was utilised to examine the data acquired from students’ linguistics background survey, daily online logs, interview transcription, and their writing products. The findings reveal that parents are the central agency facilitating language learning. During the eight-week research period, 80% of the students received interactive Extramural English, while 100% were exposed to non-interactive Extramural English. The frequency of receiving Extramural English exposure is more significant than the onset of exposure. A minimal linguistic error was recognised for 29% of average conciseness and 23% of inappropriate punctuation, while other errors were between 1% and 5%. This research highlights the importance of Extramural English exposure to written language accuracy among secondary EFL students.