Percentage of students in primary education who have their first or home language as language of instruction


Percentage of students in primary education who have their first or home language as language of instruction.

Data source

Data for this indicator may come from El Laboratorio Latinoamericano de Evaluación de la Calidad de la Educación (LLECE) 2013 (Third Regional Comparative and Explanatory Study (TERCE), Programme d'analyse des systèmes éducatifs de la confemen (PASEC) 2014 and 2018, Trends in International Mathematics and Science Study (TIMSS) 2015, and Multiple Indicator Cluster Surveys 6 (MICS6).

Source definition

UNESCO Institute for Statistics

Calculation method

Number of students in primary education who have their first language or home language as language of instruction expressed as a percentage of the total number of students at the same level stage of education and year

Data required

• Data from household surveys collecting language most often spoken at home and spoken by teachers when teaching; • Data from student assessments’ background questionnaires on language spoken at home; and • ISCED mapping by country.


The higher the percentage of children taught in their home langage, the higher the probability that they acquire cognitive skills such as beginning reading and writing. After building solid skills, learners can gradually transfer skills from the familiar language to the unfamiliar one.


The primary limitation of using international assessment data is that language of instruction is not readily available in these datasets; rather, the language of the test is used at home is reported. Generally, the language of the test for international student assessments matches the official language of instruction. Comparing estimates of the indicator across assessment programmes yielded no systematic differences, and small differences were found for countries that participated in more than one assessment programme.


Language is key to communication and understanding in the classroom. Education in the mother-tongue has been linked to improved learning outcomes. Research suggests that mother-tongue instruction improves learning outcomes including the ability of children to learn languages later in school.

Quality standards

The UIS maintains the global database on home language. The inclusion of data point in the database, it is done following a protocol for reporting the indicators, reviewed by UIS technical focal points to check for consistency and overall data quality. This review is based on a set of objective criteria to ensure that only the most recent and reliable information are included in the databases.

Types of disaggregation

Disaggregation by level of school, sex, urban or rural location and wealth (see common metadata for indicators derived from student assessment data for details on definition of these sub-populations).