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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 420 · 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.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
  2. 2.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) paper turns lemony (d) the juice scorches first
  3. 3.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
  4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) yeast (c) a cotton bud (d) a small bowl
  5. 5.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) cutting the lemon
  6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
  7. 7.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
  8. 8.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) letting the paper dry (d) ironing the paper
  9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the kind of juice (c) the same cotton bud (d) the iron setting
  10. 10.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
  11. 11.🍋 Which of these steps is a job a child can do? (a) reading the message (b) ironing the paper (c) putting the iron away (d) plugging in the iron
  12. 12.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
  13. 13.⚖️ 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
  14. 14.True or false: a balloon is not needed for the secret lemon message. (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 kind of juice (b) the iron setting (c) how dark the writing is
  16. 16.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) ironing the paper (d) plugging in the iron
  17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
  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 measure it (b) we keep it the same (c) we change it
  19. 19.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
  20. 20.⚖️ 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
  21. 21.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
  22. 22.🔮 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
  23. 23.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) a balloon (d) lemon juice
  24. 24.⚖️ 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
  25. 25.⚖️ 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
  26. 26.True or false: writing the message is a job for an adult. (a) False (b) True
  27. 27.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) rub your eyes (d) lick your fingers
  28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) white paper (d) a small bowl
  29. 29.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) brown (d) blue
  30. 30.⚖️ 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) False (b) True
  31. 31.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
  32. 32.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) the paper floats (d) writing stays faint
  33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
  34. 34.⚖️ 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
  35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
  36. 36.⚖️ 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
  37. 37.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
  38. 38.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) cutting the lemon (d) writing the message
  39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) white paper (d) a balloon
  40. 40.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) a mirror (d) turmeric powder

Answer key

  1. an adult does it
  2. the juice scorches first
  3. a child can do it
  4. yeast
  5. cutting the lemon
  6. we keep it the same
  7. not needed
  8. letting the paper dry
  9. the kind of juice
  10. not needed
  11. reading the message
  12. not needed
  13. True
  14. True
  15. the iron setting
  16. writing the message
  17. False
  18. we change it
  19. needed
  20. the same cotton bud
  21. it can burn skin
  22. almost nothing
  23. lemon juice
  24. True
  25. the same paper
  26. False
  27. wash your hands
  28. a mirror
  29. brown
  30. False
  31. an adult does it
  32. writing stays faint
  33. True
  34. we keep it the same
  35. False
  36. we keep it the same
  37. dry juice is see-through
  38. cutting the lemon
  39. a balloon
  40. an adult with an iron

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