Crossword puzzle

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Across
  1. 2. – A book that explains word meanings
  2. 5. – Money used in a particular country
  3. 8. – A triangular ancient structure built in Egypt
  4. 9. – A mountain that can erupt with lava
  5. 11. – The natural home of an animal
  6. 12. – The force that pulls objects toward Earth
  7. 16. – The process plants use to make food from sunlight
  8. 19. – One of Earth’s large land masses
  9. 20. – A type of math using letters and symbols
Down
  1. 1. – A massive system of stars and planets
  2. 3. – A vast body of saltwater covering most of Earth
  3. 4. – A number representing part of a whole
  4. 6. – The study of substances and reactions
  5. 7. – A tool used to measure temperature
  6. 10. – A vehicle with two wheels powered by pedaling
  7. 13. – A community of living organisms and their environment
  8. 14. – A person trained to travel in space
  9. 15. – Something new that has been created
  10. 17. – A tool used for navigation and direction
  11. 18. – The ability to do work or cause change