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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 576 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the ironing time (c) the kind of juice (d) the iron setting
  2. 2.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
  3. 3.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
  4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
  5. 5.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
  6. 6.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
  7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a magnet (c) lemon juice (d) a cotton bud
  8. 8.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
  9. 9.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
  10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a cotton bud (d) a mirror
  11. 11.🍋 Which of these steps is a job a child can do? (a) writing the message (b) ironing the paper (c) putting the iron away (d) cutting the lemon
  12. 12.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) white paper (d) yeast
  13. 13.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) putting the iron away (d) reading the message
  14. 14.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a cotton bud (d) a mirror
  15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
  16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we keep it the same (c) we change it
  17. 17.⚖️ 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 change it (c) we keep it the same
  18. 18.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
  19. 19.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) writing the message (c) dipping the cotton bud (d) letting the paper dry
  20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a battery cell (c) a small bowl (d) an adult with an iron
  21. 21.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a magnet (d) a cotton bud
  22. 22.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
  23. 23.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the juice scorches first (d) the iron is brown
  24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the same paper (c) the same cotton bud (d) how dark the writing is
  25. 25.True or false: ironing the paper is a job a child can do. (a) False (b) True
  26. 26.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) no, it stays brown (d) yes, in the dark
  27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) turmeric powder (d) an adult with an iron
  28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
  29. 29.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) lemon juice (d) a battery cell
  30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) white paper (d) yeast
  31. 31.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) a rainbow (d) almost nothing
  32. 32.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) a small bowl (d) a magnet
  33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
  34. 34.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
  35. 35.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) cutting the lemon (d) dipping the cotton bud
  36. 36.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a balloon (d) yeast
  37. 37.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
  38. 38.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) plugging in the iron (d) reading the message
  39. 39.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
  40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True

Answer key

  1. the kind of juice
  2. an adult does it
  3. a child can do it
  4. False
  5. only an adult
  6. a child can do it
  7. a magnet
  8. it can burn skin
  9. writing stays faint
  10. a mirror
  11. writing the message
  12. yeast
  13. putting the iron away
  14. a mirror
  15. chemical
  16. we measure it
  17. we change it
  18. dry juice is see-through
  19. ironing the paper
  20. a battery cell
  21. a magnet
  22. needed
  23. the juice scorches first
  24. how dark the writing is
  25. False
  26. no, it stays brown
  27. turmeric powder
  28. False
  29. a battery cell
  30. yeast
  31. almost nothing
  32. a small bowl
  33. False
  34. False
  35. cutting the lemon
  36. lemon juice
  37. not needed
  38. reading the message
  39. wash your hands
  40. True

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