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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 325 · 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.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) white paper (c) lemon juice (d) a cotton bud
  2. 2.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
  3. 3.⚖️ 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) False (b) True
  4. 4.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
  5. 5.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
  6. 6.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) writing the message
  7. 7.⚖️ 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
  8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) the ink is magnetic (d) it turned into air
  9. 9.⚖️ 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
  10. 10.⚖️ 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) False (b) True
  11. 11.⚖️ 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 paper (c) the kind of juice
  12. 12.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the iron is brown (d) the juice scorches first
  13. 13.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) reading the message (d) dipping the cotton bud
  14. 14.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) magnetic (d) musical
  15. 15.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
  16. 16.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
  17. 17.⚖️ 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 iron setting
  18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
  19. 19.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) writing turns green (d) the paper floats
  20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
  21. 21.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) yeast (d) a balloon
  22. 22.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
  23. 23.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
  24. 24.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
  25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) yeast (d) a cotton bud
  26. 26.⚖️ 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
  27. 27.⚖️ 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
  28. 28.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) dipping the cotton bud (d) ironing the paper
  29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a magnet (d) an adult with an iron
  30. 30.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
  31. 31.⚖️ 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) False (b) True
  32. 32.⚖️ 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
  33. 33.🧺 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) lemon juice (d) yeast
  34. 34.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is magnetic (d) it is cold
  35. 35.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) putting the iron away
  36. 36.True or false: reading the message is a job for an adult. (a) False (b) True
  37. 37.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
  38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a mirror (d) a small bowl
  39. 39.⚖️ 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 keep it the same (c) we change it
  40. 40.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a magnet (c) an adult with an iron (d) lemon juice

Answer key

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

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