The slogan, "No child left behind", became popular during the first decade of the 21st Century as the United States government sought to achieve certain ambitious benchmarks in their respective education sectors. If they were to eradicate illiteracy by a certain time frame; improve students' test scores by a certain average; and/or achieve some other benchmark, the idea was that these benchmarks would become the standards by which that country's education system could measure its effectiveness, as reflected in their students' performance.
Other countries adopted the concept, which eventually became repurposed by the United Nations across many different sectors in its crafting of the Millennium Development Goals and subsequently the Sustainable Development Goals.
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