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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 140 · 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.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
  2. 2.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
  3. 3.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) yeast (c) a battery cell (d) a mirror
  4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
  5. 5.⚖️ 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 change it (c) we measure it
  6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
  7. 7.⚖️ 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
  8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a battery cell (d) lemon juice
  9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
  10. 10.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) a balloon (d) a magnet
  11. 11.⚖️ 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
  12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
  13. 13.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
  14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
  15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
  16. 16.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) ironing the paper
  17. 17.⚖️ 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 iron setting (c) the same paper (d) how dark the writing is
  18. 18.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) reading the message (d) putting the iron away
  19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
  20. 20.⚖️ 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 keep it the same (c) we change it
  21. 21.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) paper turns lemony (d) heat adds colour
  22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a balloon (d) a cotton bud
  23. 23.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
  24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the kind of juice (c) how dark the writing is (d) the same cotton bud
  25. 25.⚖️ 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) how dark the writing is (c) the kind of juice
  26. 26.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) letting the paper dry (c) ironing the paper (d) plugging in the iron
  27. 27.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
  28. 28.True or false: writing the message is a job for an adult. (a) True (b) False
  29. 29.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
  30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) turmeric powder (d) a cotton bud
  31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
  32. 32.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
  33. 33.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) yeast (c) white paper (d) a cotton bud
  34. 34.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
  35. 35.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
  36. 36.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the ink is magnetic (d) the paper ate it
  37. 37.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a mirror (d) white paper
  38. 38.⚖️ 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
  39. 39.True or false: white paper is needed for the secret lemon message. (a) False (b) True
  40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a cotton bud (c) a small bowl (d) lemon juice

Answer key

  1. it can burn skin
  2. True
  3. an adult with an iron
  4. True
  5. we change it
  6. False
  7. True
  8. a battery cell
  9. False
  10. a cotton bud
  11. False
  12. False
  13. brown
  14. True
  15. the ironing time
  16. ironing the paper
  17. the kind of juice
  18. putting the iron away
  19. we keep it the same
  20. we keep it the same
  21. the juice scorches first
  22. a balloon
  23. a child can do it
  24. how dark the writing is
  25. the same cotton bud
  26. letting the paper dry
  27. only an adult
  28. False
  29. a child can do it
  30. turmeric powder
  31. False
  32. no, it stays brown
  33. yeast
  34. almost nothing
  35. an adult does it
  36. dry juice is see-through
  37. white paper
  38. True
  39. True
  40. a magnet

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