Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 983 · 40 questions

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.

1. 1.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
2. 2.True or false: letting the paper dry is a job for an adult. (a) False (b) True
3. 3.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) no, it stays brown (d) yes, in the dark
4. 4.⚖️ 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
5. 5.True or false: plugging in the iron is a job for an adult. (a) True (b) False
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a mirror (c) a cotton bud (d) white paper
7. 7.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a cotton bud (d) yeast
8. 8.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) putting the iron away (d) dipping the cotton bud
9. 9.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
11. 11.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
12. 12.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
13. 13.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
14. 14.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) dipping the cotton bud
15. 15.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) a magnet (d) lemon juice
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) yeast (d) a cotton bud
17. 17.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) reading the message
18. 18.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
19. 19.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
20. 20.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
21. 21.⚖️ 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) False (b) True
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) lemon juice (d) an adult with an iron
23. 23.⚖️ 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 same cotton bud (c) the kind of juice
24. 24.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) dipping the cotton bud (d) letting the paper dry
25. 25.🔮 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
26. 26.⚖️ 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
27. 27.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
28. 28.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) cutting the lemon (c) reading the message (d) writing the message
29. 29.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
30. 30.🛟 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
31. 31.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
32. 32.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) brown (d) white
33. 33.True or false: cutting the lemon is a job for an adult. (a) True (b) False
34. 34.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) a balloon (d) white paper
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) an adult with an iron (c) a cotton bud (d) white paper
37. 37.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a mirror (d) yeast
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
40. 40.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) putting the iron away (d) letting the paper dry

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