Why Senior Engineers Hate Coding Interviews

By Adam Storm

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Adam Storm

Imagine that you’re a principal at a small K-8 school who’s looking to hire a new teacher. As you have less than 20 teachers, you have to ensure that each person you hire can teach any of the grades. Adding to the complications, you’ve recently lost one of your best teachers, someone with 15 years of experience, and a mentor to many of the more junior teachers. How can you replace her?

After some thought, you craft what you think is a creative approach to interviewing. When the candidates show up, you will ask them to teach a lesson drawn from the K-8 curriculum. As you want to ensure that the candidate is well-rounded, you’ll hold off telling them about which lesson you want taught until the beginning of the interview. If they nail this, you infer that they’ll be able to easily teach anything, as they’ve clearly performed well under pressure, on a randomly selected topic.

You put notice out that you’re hiring, and some truly remarkable candidates apply. For the first test of this new approach, however, you plan to try it out on a referral, a teacher that one of your staff has worked with in the past and claims was the star of the school. You marvel at your luck that she even applied, and think that she’ll be the perfect test for your new interview process. You reach out to her to arrange an interview date, and tell her about this new technique you’re using, to allow her some chance to prepare.

Then the interview day arrives, and your candidate shows up at the school. You can sense that she’s a bit nervous, which is strange because she’s an experienced candidate with an impeccable resume. You decide not to dwell on that, and instead usher her into one of your classrooms to begin the interview. “I’d like you to teach me a lesson on Number Theory”. At that point her face sinks, because unbeknownst to you, she hasn’t taught 8th grade in more than 10 years. But always the professional, she goes to the board and starts the lesson. She talks about factors of numbers, and how to determine if a given number is divisible by 2, 5 and 10, but she’s struggling. When you ask about GCF and LCM, she needs clarification about the acronyms, which you interpret as a bad sign. You explain that you’re referring to “greatest common factor” and “least common multiple”, but at this point you can tell that her confidence is shot, and you pick a tinge of annoyance in her voice.

At the end of the hour she’s stumbled through the highlights of Number Theory, but hasn’t at all filled you with a sense of confidence that she could nail this lesson in front of a group of misbehaving 8th graders. She performs very well on several other behaviour-based interviews, but you can’t shake this feeling that maybe she’s not the best in-room teacher. After some deliberation, you decide to pass on her, and hire a much less experienced teacher who excelled on the “lesson test”.