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What the ISA is
The ISA is an annual benchmark assessment produced by the Australian Council for Educational Research, the same body that runs the PISA international study on behalf of the OECD. It was launched in 2002 and is now sat by more than 75,000 students each year across 250 international schools in 90 countries. The defining feature is that the test produces comparable scores across a globally distributed cohort, so a Year 7 reading score in Dubai is directly comparable with a Year 7 reading score in Bangkok or Brussels.
Unlike the international curriculum bodies (IB, Cambridge, College Board), ACER is not a curriculum provider. The ISA does not test the school's curriculum at all. It tests the kind of cross curricular thinking the OECD describes as functional literacy, drawing on familiar PISA style item formats. A child who has been taught well in any major international curriculum should be able to engage with the ISA without any specific preparation, which is the point.
Who sits it and when
ISA is sat by students from Year 3 to Year 10 in the schools that subscribe. The school chooses which year groups to enter, although most schools that use the ISA run it across the full range so the year on year tracking is available. The assessment runs in two main windows each year, an October window in the northern hemisphere and a March to April window that suits southern hemisphere school calendars. Schools schedule their own sitting day within the window, with the tests usually administered in the school's own classrooms over two or three sessions.
From 2018 onward the test has been delivered online for most year groups, with a small number of paper based options retained for younger children and lower bandwidth contexts. The online format adapts to the student's performance during the test, which keeps the assessment efficient and reduces the time burden. A typical sitting runs to around three hours in total, split across reading, mathematical literacy and two writing tasks.
What the test measures
The ISA covers three domains. Reading uses a mix of texts (continuous, structured, graphic) with comprehension questions that range from straightforward retrieval through inference to evaluative judgement. The mathematical literacy section uses problem based questions in plausible real world contexts rather than abstract calculation drills. The writing section asks the student to produce two pieces, one narrative or descriptive and one expository or argumentative, each marked against a published rubric by trained external markers.
Two features distinguish ISA from the school's own internal assessments. The first is the global cohort comparison: every score is reported against the wider international school population sitting the same test, which gives a frame of reference no internal assessment can provide. The second is the like school comparison: ACER reports each cohort's results against schools of similar profile (curriculum, language mix, fee tier), which controls for the fact that a school with a high proportion of native English speakers will produce different results from one with a 70 per cent ESL intake.
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How to read the parent report
The report you receive after your child has sat the ISA usually arrives three to four months after the testing window closes. It contains four useful pieces of information. The scale score in each domain, expressed on the ACER scale (which is broadly similar to the OECD PISA scale). The confidence band, which is the range within which the true score is likely to sit. The international percentile, which tells you where your child sits compared to the global ISA cohort. And the like school percentile, which compares against schools of similar profile.
The two percentiles together are the most useful number on the page. A child at the 80th percentile globally and the 55th percentile against like schools is performing strongly in absolute terms but only at the middle of their immediate peer group. The same scale score for a different child can read very differently depending on which comparison the family treats as the headline. Neither is wrong; they answer different questions. The global figure tells you how your child compares to the international school world. The like school figure tells you how your child is doing within the school they actually attend.
One number on the report rewards close attention. The writing scores are marked by external trained markers against a published rubric, which means the score is not influenced by the school's internal grading culture. If the writing score is materially below the reading score, particularly across two consecutive years, that is worth raising with the school. The most common cause is that the curriculum at that school is light on extended writing, and the gap will widen as the child moves into examination years.
How schools use the data
For the school, the ISA is primarily a school improvement instrument. The data feeds into curriculum review, particularly in literacy and mathematics, and into year on year tracking of cohort progress. A school that takes the ISA seriously will discuss the previous year's results during department meetings, will identify the items where the cohort underperformed, and will adapt the teaching to address them. A school that uses the ISA only as a marketing reference point is missing the point of the exercise.
The reporting also feeds into governance. Most schools share aggregate ISA results with their board of governors and many include selected metrics in the annual school report. Some publish their ISA percentile bands in their prospectus. The honest schools publish the like school comparison rather than the global one, because the like school comparison is the more meaningful figure for parents trying to evaluate the academic strength of a particular school.
For parents the questions worth asking on a school tour are simple. Does the school sit ISA each year. Across which year groups. What were the most recent like school percentile results. How has the school used the previous year's data. These four questions, asked directly, will tell you more about a school's academic seriousness than almost any marketing material the school produces. For the wider set of questions to ask on a school visit, see our piece on the admissions interview from a parent perspective.
ISA and admissions
ISA is not primarily an admissions test. A small number of schools refer to prior ISA results when evaluating an application from a child currently enrolled at another international school, but the assessment is not designed to function as an entry filter. The tests used at the admissions stage are different ones (CAT4, MAP, the school's own internal assessment, WIDA for English language proficiency). If you are looking at the wider admissions assessment landscape, our admissions process guide and our pieces on CAT4 and WIDA are the right starting points.
Where ISA results do play into admissions is as part of the supporting documentation a family submits when moving from one international school to another. A receiving school will routinely ask for the most recent two ISA reports along with the school report and reference. A strong ISA profile sitting alongside a strong school reference is reassuring to a receiving school and can shorten the assessment process the new school requires. A weak ISA result on its own is not a reason for refusal, but it will usually prompt a more careful conversation.
What to do with your child's ISA report
- File it: ISA reports are useful documentation if you move schools
- Read the like school percentile alongside the global one
- Compare writing against reading: a gap is worth raising with the school
- Track year on year: a one off result is less meaningful than a three year trend
- Ask the school how the previous year's cohort data shaped this year's teaching
FAQ
The International Schools Assessment is an annual benchmark test produced by ACER. It assesses reading, mathematical literacy and two forms of writing in students from Year 3 to Year 10, and compares results against the global international school cohort.
ISA is primarily a school improvement and pupil progress tool. A small number of schools refer to previous ISA results during admissions, but it is not the test you sit to gain a place. CAT4, MAP and the school's own assessments are far more common at the admissions stage.
Each pupil receives a scale score with a confidence band, a global percentile against international school peers, and a comparison against schools of similar profile. Schools receive aggregate reports that include year on year trend data.
The ISA is designed to be a benchmark, not a coached examination. Familiarity with extended reading and structured writing is the most useful preparation, alongside making sure your child is rested on the day. ACER publishes sample items on its website for any family that wants to look at the format.