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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 438 · 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 kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
  2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
  3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
  4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same paper (c) the same cotton bud (d) the iron setting
  5. 5.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
  6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) turmeric powder (d) white paper
  7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) an adult with an iron (d) yeast
  8. 8.⚖️ 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 same cotton bud (c) the kind of juice (d) the ironing time
  9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
  10. 10.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
  11. 11.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
  12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
  13. 13.🛟 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
  14. 14.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
  15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a balloon (d) white paper
  16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a mirror (c) lemon juice (d) white paper
  17. 17.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a magnet (d) lemon juice
  18. 18.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
  19. 19.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) an adult with an iron (d) lemon juice
  20. 20.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
  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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a battery cell (d) lemon juice
  23. 23.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) dipping the cotton bud (d) putting the iron away
  24. 24.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) a balloon (d) lemon juice
  25. 25.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
  26. 26.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a battery cell (c) a mirror (d) a balloon
  27. 27.True or false: cutting the lemon is a job a child can do. (a) True (b) False
  28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
  29. 29.True or false: writing the message is a job for an adult. (a) True (b) False
  30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
  31. 31.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
  32. 32.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
  33. 33.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
  34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
  35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
  36. 36.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) almost nothing (d) a rainbow
  37. 37.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) an adult with an iron (d) a battery cell
  38. 38.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) dry juice is see-through (d) it turned into air
  39. 39.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) the iron is brown (d) heat adds colour
  40. 40.⚖️ 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

Answer key

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

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