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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 940 · 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? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
  2. 2.⚖️ 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
  3. 3.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
  4. 4.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
  5. 5.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) any child (d) only an adult
  6. 6.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if cooled (d) yes, if shaken
  7. 7.True or false: putting the iron away is a job a child can do. (a) False (b) True
  8. 8.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) ironing the paper
  9. 9.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
  10. 10.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) dry juice is see-through (d) the ink is magnetic
  11. 11.⚖️ 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
  12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
  13. 13.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
  14. 14.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is cold (d) it is sticky
  15. 15.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
  16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a balloon (c) a small bowl (d) lemon juice
  17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
  18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a magnet (d) an adult with an iron
  19. 19.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
  20. 20.⚖️ 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 keep it the same (c) we measure it
  21. 21.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
  22. 22.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) turmeric powder (d) a cotton bud
  23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) yeast (d) a cotton bud
  24. 24.⚖️ 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 same cotton bud (c) how dark the writing is (d) the kind of juice
  25. 25.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) cutting the lemon (d) letting the paper dry
  26. 26.⚖️ 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
  27. 27.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) skip washing (d) rub your eyes
  28. 28.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
  29. 29.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) letting the paper dry (d) plugging in the iron
  30. 30.⚖️ 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
  31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
  32. 32.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
  33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) turmeric powder (c) a small bowl (d) lemon juice
  34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
  35. 35.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) plugging in the iron (d) cutting the lemon
  36. 36.⚖️ 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
  37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a battery cell (c) white paper (d) an adult with an iron
  38. 38.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
  39. 39.⚖️ 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) True (b) False
  40. 40.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it

Answer key

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

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