* "Élève garçon" (literally "student boy") is the most common and literal translation.
* "Garçon élève" (literally "boy student") is also grammatically correct but less commonly used.
* "Élève de sexe masculin" (literally "student of male sex") is a more formal and bureaucratic way to say it.
* You could also use "jeune garçon étudiant" (literally "young boy student") to emphasize the age of the student.
However, in most cases, it's better to simply say "élève" (student) and let the context (e.g., the conversation, the situation) imply the gender of the student.