Why ICS Bangkok Keeps Turning Its Graduates Into Teachers

Four of the adults on stage for a live taping of the Students Incorporated podcast had a strange thing in common: they used to sit in the audience's seats. Three graduated from the International Community School of Bangkok and came back to teach there. A fourth grew up watching the school take shape because her mother was one of its first teachers. The episode's own working title said the quiet part out loud, "Boomerang Alumni," and it landed on a question school systems worldwide are now scrambling to answer: when a school can't hold onto teachers, what actually works?

A Staffing Crisis With a Number Attached

The scale of the problem is no longer a guess. At the United Nations World Summit on Teachers in Santiago last September, UNESCO put a hard figure on it: the world needs to recruit more than 44 million additional primary and secondary teachers by 2030, both to meet growing enrollment and to replace the ones walking away, according to Education Week's coverage of the summit. The same UNESCO data shows primary teachers' global annual attrition rate has nearly doubled in under a decade, from 4.62 percent in 2015 to more than 9 percent by 2022. Eighteen of the 21 countries that reported data that year logged an outright shortage.

International schools carry their own, older version of this problem. A widely cited study of Near East South Asia region schools found average annual turnover of 17 percent, and a separate look at East Asia Regional Council of Schools members put it as high as 32 percent in a single year, according to a research summary published by The International Educator. Unlike a public school district losing a teacher to the school across town, an international school losing a hire often loses someone it flew in, relocated, and onboarded at real expense, costs domestic systems rarely have to absorb at all. Bangkok's expatriate-heavy school market is not exempt from that math.

ICS Bangkok's answer, at least on the evidence of one November taping, wasn't a slicker recruiting fair. It was people who never really left.

The Teachers Who Came Back

Mrs. Asia graduated from ICS in 2015 and returned to teach middle school visual arts by 2019, "as soon as I could," she said on air, before stepping away from the classroom this past year after having a baby. Gersom de Koning, who goes by Mr. G, has a longer history with the school: he was a student when ICS moved onto its current campus in ninth grade and graduated in 2008. He didn't train as a teacher. He studied event management and theater in the Netherlands, worked in applied theater with teenagers, and was preparing to launch his own coaching and acting business in Singapore when a message arrived from a former ICS staff member, Mr. Darren, asking if he'd consider teaching at ICS "even if it was just one year." De Koning talked it over with his wife, who was expecting their first child, and agreed to try it. He's now in his sixth year, and credits the decision to stay less to the job itself than to the administrators above him: he singled out "Mr. Luke" and "Ms. Amber" by name as the reason he kept renewing his contract.

Mr. Tent, the newest of the four, graduated in 2013 and spent two years as a teaching assistant at a nearby Bangkok school before returning to ICS this year as a full-time PE teacher, his first year in that role. Mrs. Lin didn't graduate from ICS at all; she attended Dulat International School in Malaysia, but her mother has taught at ICS since its founding year, first as a third-grade teacher and later as elementary principal, and Lin grew up wandering the campus helping set up her mother's classroom. She now teaches geometry, a position she started that January.

None of the four described their return as an obvious plan. It reads, in their own telling, more like a series of small pulls back toward a place that already knew them.

The Recruiting Channel That Isn't a Job Board

What got them there wasn't a posting on an international-teaching job site. It was a text from a former colleague, a family connection decades deep, or simply never having fully left the building. That mechanism has a name in workforce research now, and it's suddenly one of the hottest topics in hiring: the boomerang employee.

Data from payroll processor ADP found that 35 percent of new hires in March 2025 were people returning to an employer they'd worked for before, up from 31 percent the year prior, according to reporting from HRMorning. In competitive fields, the share is even higher: roughly one in five of Google's AI software engineering hires in 2025 were former employees rejoining the company, per the same report. Employers are leaning into it because the numbers are hard to ignore: a returning hire onboards faster, arrives with institutional trust already built, and by several measures sticks around longer than an outside hire recruited cold.

Education researchers have documented a parallel version of this for schools, usually under the banner of "Grow Your Own" teacher pipelines: programs that recruit and train people already rooted in a school community to become its teachers, rather than importing them. A 2025 study by Danielle Sanderson Edwards and Matthew Kraft, published in the peer-reviewed journal Review of Educational Research, examined 94 such programs and found they vary enormously in design, but that teachers who come up through them tend to stay in their districts longer than teachers hired the conventional way. ICS's version of this wasn't a formal program with an application form. It was a former teacher who happened to remember a promising theater kid, and a school small and connected enough that the message could still reach him years later in Singapore.

"I still call some of them Mr. and Mrs., and I call some of them just by their first name. I'm trying to figure it out."

That's Mr. Tent, describing the strangest part of his first year back: figuring out what to call the adults who used to be his teachers. It's a small detail, but it points to something the retention research doesn't always capture: coming back to teach at your old school isn't just a staffing decision, it's a renegotiation of identity in a building that still remembers who you used to be.

What the Model Can't Manufacture

It would be easy to oversell four teachers on one stage as a strategy. ICS didn't publish a "Grow Your Own" pipeline document, and nothing in the episode suggests the school set out with a formal plan to recruit its own alumni. What the conversation shows instead is a byproduct of something schools can't shortcut: a campus small and stable enough that a 2008, 2013, and 2015 graduate all still had a working relationship with the adults who might invite them back, and a family connection deep enough that a non-alumna felt like an insider anyway. That's a harder thing to build than a bonus program, and it's exactly the kind of asset the turnover data suggests most international schools are short on.

The four teachers on stage that day didn't frame their return as a fix for a global shortage they'd likely never heard quantified. De Koning talked about supportive bosses. Mrs. Asia talked about timing. Lin talked about a mother who, alongside the headmaster, once sold ice cream to students at lunch on a campus that flooded to the knees, a small ritual Lin says built a sense of belonging. But together, their stories are a working example of what researchers are now urging systems everywhere to build deliberately: a reason for the people a school already shaped to come back and shape the next group themselves.

Whether that model scales past a single alumni-heavy campus in Bangkok is an open question the data hasn't answered yet. What ICS has, for now, is four people willing to be evidence.

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