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Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 826 · 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 not needed for the secret lemon message? (a) a small bowl (b) turmeric powder (c) an adult with an iron (d) a cotton bud
  2. 2.⚖️ 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
  3. 3.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) writing the message (c) putting the iron away (d) ironing the paper
  4. 4.🔮 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
  5. 5.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
  6. 6.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
  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 kind of juice (b) the ironing time (c) the iron setting (d) the same cotton bud
  8. 8.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
  9. 9.⚖️ 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 kind of juice (c) the same cotton bud
  10. 10.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) putting the iron away (d) letting the paper dry
  11. 11.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) plugging in the iron (d) writing the message
  12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
  13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
  14. 14.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) white paper (d) a balloon
  15. 15.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
  16. 16.⚖️ 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
  17. 17.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) plugging in the iron (d) ironing the paper
  18. 18.🛟 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
  19. 19.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
  20. 20.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) putting the iron away (d) ironing the paper
  21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) lemon juice (d) a mirror
  22. 22.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) musical (d) chemical
  23. 23.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
  24. 24.⚖️ 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 measure it (c) we keep it the same
  25. 25.⚖️ 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
  26. 26.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
  27. 27.⚖️ 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 ironing time (d) the iron setting
  28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) a cotton bud (d) white paper
  29. 29.🍋 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
  30. 30.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
  31. 31.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) reading the message (d) ironing the paper
  32. 32.⚖️ 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
  33. 33.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) yes, in the dark (d) no, it stays brown
  34. 34.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
  35. 35.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
  36. 36.⚖️ 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
  37. 37.⚖️ 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
  38. 38.⚖️ 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
  39. 39.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
  40. 40.⚖️ 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 keep it the same (c) we measure it

Answer key

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

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