At the start of the second term, preparations for the sports festival begin. The students are nervous about the fact that performance in the events will affect their written tests, and even more pressure is added by the unique team breakdowns and freedom given to the students to decide who takes part in what event...
The error could have come from 
a student not under his control.
ربما أتى الخطأ من تلميذٍ
ليس تحت سيطرته
Könnte also ein Fehler eines Schülers sein,
der nicht unter seiner Kontrolle steht.
También pudo equivocarse
alguno de los que él controla.
También pudo equivocarse
alguno de los que controla él.
Un élève échappant à son contrôle
a dû échouer.
Forse è stato proprio qualcuno fuori 
dal suo controllo a indurlo in errore.
O erro pode ter vindo de um estudante
que não está sob comando dele.
Похоже, вариант с ошибкой недовольного
отбрасывать нельзя…