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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 836 · 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.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) lemon juice (d) a battery cell
  2. 2.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) plugging in the iron
  3. 3.⚖️ 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 measure it (c) we change it
  4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
  5. 5.⚖️ 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
  6. 6.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
  7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we keep it the same (c) we change it
  8. 8.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
  9. 9.⚖️ 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
  10. 10.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) putting the iron away (d) ironing the paper
  11. 11.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
  12. 12.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
  13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud (d) the ironing time
  14. 14.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
  15. 15.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
  16. 16.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) plugging in the iron (d) ironing the paper
  17. 17.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
  18. 18.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
  19. 19.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a magnet (d) white paper
  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) the iron setting (c) how dark the writing is
  21. 21.⚖️ 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) the same paper (d) the kind of juice
  22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) white paper (d) lemon juice
  23. 23.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
  24. 24.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
  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.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words
  27. 27.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
  28. 28.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is sticky (d) it is magnetic
  29. 29.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) whoever is fastest (d) any child
  30. 30.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) ironing the paper (d) reading the message
  31. 31.⚖️ 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
  32. 32.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) plugging in the iron (d) letting the paper dry
  33. 33.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
  34. 34.⚖️ 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
  35. 35.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
  36. 36.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
  37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a small bowl (d) turmeric powder
  38. 38.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) letting the paper dry (c) plugging in the iron (d) putting the iron away
  39. 39.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
  40. 40.⚖️ 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 change it (c) we measure it

Answer key

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

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