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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 249 · 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.⚖️ 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
  2. 2.🔮 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
  3. 3.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
  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 change it (b) we measure it (c) we keep it the same
  5. 5.⚖️ 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
  6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the kind of juice (c) the ironing time (d) the same cotton bud
  7. 7.⚖️ 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) the same paper (c) how dark the writing is (d) the kind of juice
  8. 8.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
  9. 9.True or false: white paper is needed for the secret lemon message. (a) True (b) False
  10. 10.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
  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 iron setting (c) the kind of juice
  12. 12.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) reading the message (d) writing the message
  13. 13.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
  14. 14.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) musical (d) physical
  15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
  16. 16.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
  17. 17.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
  18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) a magnet (d) lemon juice
  19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a cotton bud (c) white paper (d) lemon juice
  20. 20.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) the iron is brown (d) heat adds colour
  21. 21.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) cutting the lemon (d) putting the iron away
  22. 22.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
  23. 23.⚖️ 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
  24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) an adult with an iron (d) lemon juice
  25. 25.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) putting the iron away
  26. 26.🛟 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
  27. 27.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) turmeric powder (d) a small bowl
  28. 28.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
  29. 29.True or false: letting the paper dry is a job a child can do. (a) True (b) False
  30. 30.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) writing the message (d) cutting the lemon
  31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
  32. 32.🔮 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
  33. 33.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green
  34. 34.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
  35. 35.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
  36. 36.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) ironing the paper
  37. 37.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
  38. 38.⚖️ 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 keep it the same (c) we change it
  39. 39.⚖️ 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
  40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) white paper (d) an adult with an iron

Answer key

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

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