Shadowing an interview — and meeting a former student again
There are moments when years of teaching suddenly feel very meaningful. For me, that was sitting quietly while a former student passed a System Design round right in front of me.
There are some moments that, even after several years of working, I still feel something special when I look back on them — happiness, pride, a sudden clarity that the teaching I'd been doing actually meant something.
One of those moments happened in late 2024, just after I'd joined a new company.
Sitting quietly in a corner
That day I sat in on a hiring interview, but not in the main seat. I was a shadow interviewer — observing, sitting quietly in a corner, not asking questions, not scoring. A purely "outside" role.
The candidate walked in, and I recognized him — a former student from the System Design course that I, along with two friends (anh Việt and anh Hoà), had taught earlier.
The feeling in that moment was hard to put into words. Happy to see a former student again, in a completely different setting. A little nervous too — "If he doesn't do well, is this going to be awkward?"
The System Design gate
The interview went normally — technical questions, experience questions, situational questions. I sat there, observing quietly.
Things went steadily until the hardest part — System Design. This is always the gate a lot of people dread, because it doesn't only test knowledge — it tests systems thinking, communication, and how you steer a problem.
The prompt came up. And that's when I saw the difference.
He started off very steadily:
- Asked clarifying questions first. About scale. About the system's goals. About the constraints to consider. That approach showed both care and an ability to look at a problem from multiple angles.
- Broke the problem down and built each architectural layer. At every step, he explained why he picked an option, what its pros and cons were, and how it would scale up.
- Stayed coherent. There were moments he had to pause and think, but he never lost his composure or got pulled into trivial details.
I could see it clearly: what he had learned in the course was no longer theory. It had become a field-tested skill. He used it naturally — no forced phrasing, no rote answers.
The teacher off-stage
From the observer's seat, there was nothing I could do to help. But I felt at ease.
Like a teacher watching a student perform confidently from offstage. Knowing I'd only contributed a small part to his journey — but enough to feel a quiet warmth.
The interview ended. I wasn't the scorer, but seeing the lead interviewer's satisfied expression, I knew he had made a strong impression.
About two weeks later I got a message:
"Anh, I passed. I just got the offer!"
I sat still for a while after reading that. Not the loud kind of happy — the quiet kind, that feels like something has come full circle.
A small belief, reaffirmed
That story reaffirmed something for me: System Design isn't a CV decoration, and it isn't something to study just to say you did. It's a real key — it opens the hardest interview round, the one that asks not just for knowledge, but for thinking, communication, and calm under pressure.
And more than that, System Design lets an engineer prove they don't only know how to code — that they understand and can steer how large systems actually work. A quality every company looks for.
Whenever I look back on that day, I still see him sitting there, working through the problem step by step with a steady voice and focused eyes. An ordinary interview. But for me, it was the moment both teacher and student got paid back for the effort.
And it reminded me — sometimes a course, studied properly and applied fully, can become a launch pad for a new chapter in someone's career.
If this piece was useful — buy me a coffee. It's what keeps me writing.