← Lemon juice invisible ink lesson New set →

Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 649 · 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.

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

Answer key

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

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids