In this guide
Why teacher quality dominates
Educational research over the past three decades repeatedly arrives at the same conclusion. The single largest in-school factor affecting student outcomes is the quality of the individual teacher. A child placed with strong teachers for three consecutive years can gain a year of learning relative to peers placed with weaker ones, all else being equal. Class size, facilities, curriculum and class composition matter, but teacher quality matters more than all of them combined.
This has uncomfortable implications for international schools. Premium fees pay for marble lobbies, library catalogues and athletics centres, none of which is the strongest lever on what your child actually learns. The strongest lever is the human in front of the classroom 25 hours a week. Schools that invest in their teachers (selection, induction, professional development, retention) produce better outcomes than schools that invest in their buildings.
Qualifications and what they tell you
At credible international schools, classroom teachers hold a formal teaching qualification: PGCE or QTS in the UK, an Education degree and state teaching license in the US, equivalent qualifications from Canada, Australia and elsewhere. Many also hold a subject Master's, particularly at sixth-form level. Schools that publish faculty bios on the website are signalling confidence in their staff. Schools that publish nothing about their teachers are usually hiding something.
Specialist subjects sometimes use teachers without formal qualifications: native-speaker language assistants, peripatetic music teachers, sports coaches with elite-performance backgrounds rather than teaching certificates. This is normal and not a warning sign. What is a warning sign is core-subject teachers (maths, English, science) without recognised teaching qualifications.
Faculty retention: the leading indicator
Faculty retention is the single best leading indicator of school health. Ask the school for the percentage of teachers who departed at the end of the previous academic year. The benchmarks below are based on the schools we work with.
Below 10 percent annual turnover
Exceptional retention, typically seen at the most established schools (Dubai College, Tanglin Trust, Lycée Français Charles de Gaulle, ZIS Zurich). Strong signal of leadership quality, package competitiveness and pastoral culture. Difficult to maintain over a decade.
10 to 18 percent annual turnover
Healthy range for international schools running on contract cycles. Most expat teachers complete a 2 to 3 year contract and renew once; those who do not renew typically leave after one cycle. Indicates a school with structural turnover but no underlying problem.
18 to 25 percent annual turnover
Elevated. Sometimes explained by region (high-rotation expat markets) or by a leadership transition. Ask why. If the school cannot explain the pattern, that itself is the signal.
Above 25 percent annual turnover
Warning sign. Schools at this level usually have one of three issues: poor leadership, uncompetitive package, or pastoral culture problems among the staff. Ask the school directly, ask current parents privately, read recent inspection reports. A school sustaining this rate over multiple years is not a stable school.
Read parent reviews on our review database
Our verified parent reviews are a useful second source on teacher quality, particularly the comments that surface repeatedly across different reviewers for the same school. Combined with a free advice call with our team, this is usually enough to triangulate what a school's recruitment material is and is not telling you.
The expat teacher cycle
Many international schools run on a contract cycle: teachers are hired on 2 or 3 year contracts, often with relocation support and accommodation. Most renew at least once; some stay for a decade. This produces predictable turnover that is not in itself a problem. What matters is what the school does with it.
Strong schools recruit a year ahead, using long-established networks (Search Associates, ISS-Schrole, COBIS recruitment fairs) to identify teachers with international experience and the right subject specialism. They invest heavily in induction (a one-week pre-term programme is standard), assign mentors to new arrivals, and keep classroom assignments deliberately stable in the first year. Schools that hire late, induct lightly and rotate teachers across year groups within a year are losing the benefit of their own recruitment cycle.
The other dimension is the senior teacher cadre. Even a school with 18 percent turnover can be stable if the heads of department, the heads of year and the most experienced teachers have been there for 5 to 10 years. Ask specifically about the tenure of department heads in your child's likely subjects.
What to look for in a classroom
If you can observe a class on a school tour, watch four things. First, how often the teacher asks questions of the class versus delivering content. A strong teacher uses questioning to surface understanding and confusion; a weak teacher talks at the class. Second, whether the teacher is attending to all the children in the room or only the responsive few in the front rows. The signal is in how the teacher engages the quieter half of the class.
Third, how the teacher responds when a child gets something wrong. Strong teachers probe the wrong answer (often it is the most useful teaching moment). Weak teachers move on quickly. Fourth, the texture of the classroom: are children writing, talking, listening, working on screens, all four. Variety usually signals teacher craft; uniformity often signals one-pace whole-class instruction.
This observation is more valuable than any test score the school can show you. Many schools will arrange a class observation if asked politely in advance.
Senior staff and stability
Below the head of school, the people who shape the daily experience are the deputy head, the heads of primary and secondary, the head of pastoral care, and the head of admissions. Ask how long each has been in post. Schools where the senior team has 3 to 7 years of tenure each are usually well led; schools where most of the senior team arrived within the last 18 months are often in transition. Transitions can produce strong schools but they introduce volatility.
The head of school tenure deserves separate attention. The international school average head tenure runs 3 to 5 years. Heads in post for less than 2 years should be asked about their plan; heads in post for 7+ years are usually either exceptional or stale. Ask current parents which one applies. For the broader picture see our piece on how to choose an international school.
Questions to ask the school
Ask for the annual turnover rate for each of the past three years. Ask specifically how many teachers in your child's likely year group are returning next year. Ask what the average length of service is for current teachers, broken down by primary and secondary. Ask how the school inducts new teachers. Ask how often heads of department meet to discuss teaching practice. Ask whether the school runs formal teacher development (lesson study, coaching, peer observation) and what percentage of teachers participate. The detail of the answers, not just the figures, tells you what you need to know. See also our piece on class size at international schools for related signals.
Frequently asked questions
What teacher turnover rate is normal at an international school?
International schools running on two or three year contracts often see 15 to 20 percent annual turnover. Schools with longer contracts and stronger retention strategies sit at 8 to 12 percent. Anything above 25 percent annually is a warning sign.
Do international school teachers need a formal teaching qualification?
At credible schools, yes. PGCE, QTS, US teaching license or equivalent is standard. Some schools hire unqualified teachers for specialist subjects or for language assistant roles; this should be transparent.
How can parents assess teacher quality on a school tour?
Observe a class in session if possible. Watch how teachers manage attention, ask questions and respond to students. Ask about teacher tenure in your child's year group specifically. Ask how new teachers are inducted and mentored.
Is teacher quality more important than class size or curriculum?
Yes. Decades of research on educational outcomes show that the quality of the individual teacher is the single largest in-school factor affecting student learning. Class size and curriculum matter, but teacher quality dominates.