The Horace Mann League (HML) and the National Superintendents Roundtable have published a fascinating report called School Performance: The Iceberg Effect.  I would recommend reading the full report but an Executive Summary is also available – both can be found here.

They wrote the study because of their concerns about the use of international large-scale education assessments (ILSA) such as PISA to compare countries.  As educators, we cringe when newspapers and critics boil down the success of a child, let alone a country, on the results of a test.  They cite several research studies which indicate that up to 70% of tested achievement can be accounted for by out-of-school factors.  Hence The Iceberg Effect – a tendency focus on the part of the iceberg we can see when the part we can’t see is so much more important.

In their report, the part of the iceberg we can see are Student…