Number of students per teacher during the reporting period.
Number of students per teacher during the reporting period.
Organizations should footnote all assumptions used.
This metric is intended to capture the ratio of students to teachers during the reporting period, often used as a proxy of teacher workload, educational investment, or instructional efficiency.
In some contexts, this metric can serve as an indicator of whether the outcome being sought by an investor or organization is occurring (the WHAT dimension of impact). For more on the alignment of IRIS metrics to the five dimensions of impact, see IRIS+ and the Five Dimensions of Impact (https://iris.thegiin.org/document/iris-and-the-five-dimensions/). No single metric is sufficient to understand an impact; rather, metrics are selected as a set across all dimensions of impact. When possible, the selection of metrics to measure and describe the five dimensions should be based on best practice and evidence.
June 2022 - IRIS v5.3 Released (current version)
Immaterial change. Minor revision to usage guidance for clarity.
January 2020 - IRIS v5.1 Released
No change.
May 2019 - IRIS v5.0 Released
No change.
March 2016 - IRIS v4.0 Released
No change.
March 2014 - IRIS v3.0 Released
No change.
November 2011 - IRIS v2.2 Released
No change.
February 2011 - IRIS v2.1 Released
No change.
September 2010 - IRIS v2.0 Released
Immaterial change. IRIS ID changed due to framework upgrade. Minor revision to definition language for clarity.
September 2009 - IRIS v1.0 Released
New metric. Student to Teacher Ratio (ED17) was developed via the Original IRIS Working Group.