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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 218 · 40 questions
TalentJR

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

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  1. 1.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
  2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
  3. 3.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) blue words (d) dark brown words
  4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the ironing time
  5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same paper (c) how dark the writing is (d) the iron setting
  6. 6.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
  7. 7.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) ironing the paper
  8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) the paper ate it (d) dry juice is see-through
  9. 9.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
  10. 10.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
  11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
  12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a magnet (d) a small bowl
  13. 13.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
  14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
  15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the same cotton bud (c) the kind of juice
  16. 16.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) a balloon
  17. 17.True or false: plugging in the iron is a job for an adult. (a) True (b) False
  18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
  19. 19.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
  20. 20.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) letting the paper dry (c) reading the message (d) dipping the cotton bud
  21. 21.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
  22. 22.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) yeast (d) lemon juice
  23. 23.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a small bowl (c) a magnet (d) yeast
  24. 24.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) plugging in the iron (d) cutting the lemon
  25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
  26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
  27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a battery cell (c) a small bowl (d) an adult with an iron
  28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the kind of juice (c) how dark the writing is (d) the same paper
  29. 29.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
  30. 30.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
  31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a small bowl (c) white paper (d) a cotton bud
  32. 32.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
  33. 33.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
  34. 34.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
  35. 35.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
  36. 36.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) writing the message
  37. 37.True or false: reading the message is a job a child can do. (a) False (b) True
  38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
  39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
  40. 40.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown

Answer key

  1. only an adult
  2. we keep it the same
  3. almost nothing
  4. the ironing time
  5. the kind of juice
  6. writing stays faint
  7. reading the message
  8. dry juice is see-through
  9. a child can do it
  10. a child can do it
  11. False
  12. a magnet
  13. an adult does it
  14. we keep it the same
  15. the same cotton bud
  16. a balloon
  17. True
  18. False
  19. wash your hands
  20. ironing the paper
  21. an adult does it
  22. lemon juice
  23. a small bowl
  24. letting the paper dry
  25. we change it
  26. True
  27. a battery cell
  28. how dark the writing is
  29. not needed
  30. letting the paper dry
  31. a magnet
  32. False
  33. an adult does it
  34. True
  35. a child can do it
  36. writing the message
  37. True
  38. we measure it
  39. False
  40. the juice scorches first

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