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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 129 · 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) lemon juice (b) turmeric powder (c) a small bowl (d) a cotton bud
  2. 2.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
  3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
  4. 4.⚖️ 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
  5. 5.True or false: reading the message is a job a child can do. (a) False (b) True
  6. 6.True or false: putting the iron away is a job a child can do. (a) False (b) True
  7. 7.⚖️ 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 same cotton bud (c) the iron setting (d) how dark the writing is
  8. 8.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) writing the message
  9. 9.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
  10. 10.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) writing the message
  11. 11.⚖️ 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
  12. 12.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
  13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) lemon juice (d) a small bowl
  14. 14.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) it turned into air (d) the ink is magnetic
  15. 15.⚖️ 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 change it (c) we keep it the same
  16. 16.⚖️ 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
  17. 17.⚖️ 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
  18. 18.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) white (d) green
  19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
  20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
  21. 21.⚖️ 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
  22. 22.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
  23. 23.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
  24. 24.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if shaken (d) yes, if cooled
  25. 25.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
  26. 26.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) white paper (c) a cotton bud (d) an adult with an iron
  27. 27.⚖️ 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
  28. 28.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) dipping the cotton bud
  29. 29.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) ironing the paper (d) cutting the lemon
  30. 30.⚖️ 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 measure it (c) we keep it the same
  31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a cotton bud (c) white paper (d) a small bowl
  32. 32.🛟 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
  33. 33.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
  34. 34.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) chemical (d) magnetic
  35. 35.⚖️ 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
  36. 36.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
  37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) how dark the writing is (c) the same paper (d) the ironing time
  38. 38.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
  39. 39.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) dipping the cotton bud (d) writing the message
  40. 40.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it

Answer key

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

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