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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 955 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) yeast
  2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the iron setting (c) how dark the writing is
  3. 3.⚖️ 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) True (b) False
  4. 4.🍋 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
  5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same paper (c) how dark the writing is
  6. 6.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
  7. 7.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a mirror (d) a cotton bud
  8. 8.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
  9. 9.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a mirror (d) a small bowl
  10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
  11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) an adult with an iron (d) a mirror
  12. 12.⚖️ 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
  13. 13.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) dipping the cotton bud (d) writing the message
  14. 14.True or false: plugging in the iron is a job a child can do. (a) False (b) True
  15. 15.True or false: ironing the paper is a job for an adult. (a) False (b) True
  16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the kind of juice (c) the ironing time (d) how dark the writing is
  17. 17.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) paper turns lemony (d) the juice scorches first
  18. 18.⚖️ 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 measure it (c) we keep it the same
  19. 19.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
  20. 20.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
  21. 21.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) yes, in the dark (d) no, it stays brown
  22. 22.⚖️ 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 measure it (c) we keep it the same
  23. 23.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) a rainbow (d) blue words
  24. 24.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) yeast (d) turmeric powder
  25. 25.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
  26. 26.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) writing the message (d) cutting the lemon
  27. 27.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) putting the iron away
  28. 28.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) chemical (d) magnetic
  29. 29.⚖️ 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
  30. 30.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
  31. 31.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
  32. 32.⚖️ 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 same paper (d) the kind of juice
  33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud
  34. 34.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) writing the message
  35. 35.True or false: white paper is needed for the secret lemon message. (a) True (b) False
  36. 36.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) skip washing (d) rub your eyes
  37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) lemon juice (d) a battery cell
  38. 38.True or false: writing the message is a job a child can do. (a) False (b) True
  39. 39.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
  40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False

Answer key

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

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