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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 369 · 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.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
  2. 2.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) reading the message (c) ironing the paper (d) putting the iron away
  3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
  4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
  5. 5.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) it gets darker (d) the paper floats
  6. 6.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
  7. 7.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
  8. 8.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
  9. 9.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
  10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) any child (d) only an adult
  11. 11.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
  12. 12.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) reading the message (d) dipping the cotton bud
  13. 13.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
  14. 14.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) musical (d) chemical
  15. 15.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) the juice scorches first (d) heat adds colour
  16. 16.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) cutting the lemon (d) plugging in the iron
  17. 17.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) cutting the lemon
  18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) blue words (d) dark brown words
  19. 19.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
  20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the iron setting (c) the kind of juice (d) the same paper
  21. 21.⚖️ 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) True (b) False
  22. 22.True or false: ironing the paper is a job for an adult. (a) True (b) False
  23. 23.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
  24. 24.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it can burn skin (d) it is sticky
  25. 25.⚖️ 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 iron setting (c) how dark the writing is (d) the ironing time
  26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
  27. 27.⚖️ 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 measure it (c) we keep it the same
  28. 28.🍋 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
  29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
  30. 30.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) plugging in the iron (d) reading the message
  31. 31.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a balloon (d) a cotton bud
  32. 32.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) a mirror (d) an adult with an iron
  33. 33.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) a magnet (d) lemon juice
  34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
  35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
  36. 36.⚖️ 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
  37. 37.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) dipping the cotton bud (d) reading the message
  38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) lemon juice (d) a cotton bud
  39. 39.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
  40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) lemon juice (d) a balloon

Answer key

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

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