Classroom fact library
3,762 facts for lessons, each with its source and retrieval date. We publish a value only when it has a named source; when two sources disagree, we leave it out. Turn any topic into a free worksheet, quiz and flashcards, with no AI involved.
Fact of the day
The capital of Guyana is Georgetown.
Verified Source: CIA World Factbook, retrieved 2026-10-26 · GeoNames, retrieved 2026-10-26 (as of 2026-01-22)
Topics
- Countries: capitals, continents and languages
Capitals, continents, official languages and flag descriptions for the world's countries, with the source of every fact.
Grades 3–12708 facts371 verified337 sourced
- The periodic table of elements
All named chemical elements with their symbols, atomic numbers, standard atomic weights (IUPAC 2021), periods, groups and blocks, cross-checked in two sources.
Grades 6–12767 facts425 verified342 sourced
- The planets of the solar system
Diameter, mass, gravity, day length, year length, distance from the Sun and average temperature of the eight planets, from NASA's planetary fact sheet.
Grades 4–1272 facts72 sourced
- Moons of the planets
Moons of the solar system's planets with the planet each one orbits and its mean radius, from NASA JPL.
Grades 3–12344 facts344 sourced
- US states and capitals
All 50 US states and their capital cities, from the US Geological Survey's National Map.
Grades 3–1250 facts50 sourced
- Units of measurement and conversions
Exact customary and metric unit conversions for length, mass, capacity, time and area, each checked in two independent unit-definition sets.
Grades 2–1231 facts31 verified
- World landmarks (World Heritage Sites)
Famous World Heritage Sites and the country each one is in, as listed in the CIA World Factbook.
Grades 4–121,728 facts1,728 sourced
- Vocabulary lists
Science, geography and maths vocabulary lists with short definitions written for pupils.
Grades 2–862 factsour own wording
How we check facts
- Verified Two independent sources give the same value (for example the CIA World Factbook and GeoNames for a capital), or the body that defines the value published it and we read it from them directly.
- Sourced One named source with a reference, such as NASA's planetary fact sheet.
- Our wording Vocabulary definitions written by our team in plain words for pupils; not copied from a dictionary.
- Values without a reference, and values where sources disagree, are not published. Facts that change (capitals being moved, for example) show the date they were true as of, and are left out of quizzes for younger pupils.
- We use only sources whose licences allow it: public-domain US Government data, CC0 data, and CC BY data with credit. We don't use Wikipedia text or other share-alike or non-commercial material.
Data compiled 2026-10-26.