Science Crossword Puzzle

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Across
  1. 2. a property of a material that does not allow light to pass through
  2. 5. a mammal that lays eggs
  3. 7. a measurement of how hot or cold something is
  4. 13. a bird that does not fly but swim very well
  5. 14. a magnet has North pole and?
  6. 15. a vital organ in our body that pumps blood throughout the body
  7. 17. non-flowering plants reproduced by _______
  8. 18. a system in our body that breaks down food to give us energy
  9. 20. a system in our body that protects vital organs
Down
  1. 1. the main source of energy
  2. 3. heat travels from a _______ place to a colder place
  3. 4. it has two poles
  4. 6. a property of a material that allows some light to pass through
  5. 7. a property of a material that allows most light to pass through
  6. 8. a system in our body that enables us to move
  7. 9. the hard outer covering of insects
  8. 10. when material bends easily without breaking
  9. 11. living things need air, food and ______
  10. 12. a method that is used to turned magnetic material into a magnet
  11. 16. thermometer must be held _______ when measuring the temperature of an object
  12. 19. this is formed when light is blocked