Simple English Wikipedia

Simple English Wikipedia is a sister project of the main Wikipedia, run by the Wikimedia Foundation and written entirely by volunteers. It began in 2001 and holds roughly 285,000 articles, all written in simplified English: shorter sentences, plainer words and easier grammar than the standard edition. It is not Ogden's formal Basic English, but a house style aimed at learners, younger readers and anyone reading English as a second language.

You can browse it at simple.wikipedia.org, or take the whole thing as a database dump from dumps.wikimedia.org under the simplewiki code, in the same raw wikitext, parsed HTML and SQL forms as every other Wikimedia project. Because the edition is small, the compressed article text is well under a gigabyte, so it downloads and parses quickly. A pre-cleaned, one-article-per-record copy also ships in the wikimedia/wikipedia dataset on the Hugging Face Hub as the simple configuration.

For RAG the appeal is a compact, broad-coverage corpus that stands up a retrieval pipeline in minutes rather than the tens of gigabytes of the full English dump. For an AI tutor the value is the reading level itself: the same encyclopaedic facts, pitched low, give a model a ready register for explaining a concept to a beginner before stepping up to denser sources. It works well as a plain-language glossary and definition layer, and as level-graded reference to sit under the structured curricula we already list, such as openstax, ck-12, siyavula and khan-academy, or beside standards like common-core and ngss when you want the underlying idea explained simply. It is general knowledge, not mathematics, so it complements rather than overlaps the maths sets (amps, stackmathqa, megamath, openthoughts3, naturalproofs) and the law-focused case-network.

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