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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 506 · 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 cotton bud (b) yeast (c) white paper (d) lemon juice
  2. 2.⚖️ 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 cotton bud (c) the kind of juice
  3. 3.🛟 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
  4. 4.⚖️ 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
  5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a small bowl (c) lemon juice (d) a cotton bud
  6. 6.⚖️ 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
  7. 7.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
  8. 8.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) letting the paper dry (d) cutting the lemon
  9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
  10. 10.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) writing the message (d) dipping the cotton bud
  11. 11.🔮 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
  12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) yeast (c) a small bowl (d) white paper
  13. 13.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a battery cell (c) turmeric powder (d) a balloon
  14. 14.⚖️ 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 ironing time (c) the iron setting (d) how dark the writing is
  15. 15.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
  16. 16.⚖️ 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
  17. 17.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) whoever is fastest (d) the youngest child
  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 change it (c) we measure it
  19. 19.🔮 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
  20. 20.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
  21. 21.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
  22. 22.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
  23. 23.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) ironing the paper (d) putting the iron away
  24. 24.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
  25. 25.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
  26. 26.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) a cotton bud (d) a balloon
  27. 27.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
  28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) how dark the writing is (c) the kind of juice (d) the ironing time
  29. 29.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
  30. 30.⚖️ 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 change it (c) we measure it
  31. 31.⚖️ 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
  32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
  33. 33.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
  34. 34.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) a battery cell (d) yeast
  35. 35.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) yeast (d) a balloon
  36. 36.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a magnet (d) a cotton bud
  37. 37.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
  38. 38.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it can burn skin (d) it is sticky
  39. 39.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) plugging in the iron (d) dipping the cotton bud
  40. 40.🍋 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) putting the iron away

Answer key

  1. yeast
  2. the same cotton bud
  3. wash your hands
  4. we change it
  5. a mirror
  6. True
  7. True
  8. letting the paper dry
  9. we measure it
  10. ironing the paper
  11. almost nothing
  12. yeast
  13. white paper
  14. how dark the writing is
  15. dry juice is see-through
  16. True
  17. only an adult
  18. we keep it the same
  19. no, it stays brown
  20. writing stays faint
  21. a child can do it
  22. False
  23. reading the message
  24. an adult does it
  25. True
  26. a cotton bud
  27. needed
  28. the kind of juice
  29. a child can do it
  30. we keep it the same
  31. the same paper
  32. False
  33. an adult does it
  34. a small bowl
  35. lemon juice
  36. a magnet
  37. needed
  38. it can burn skin
  39. plugging in the iron
  40. putting the iron away

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