Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 87 · 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.⚖️ 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 paper (c) the kind of juice
2. 2.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
3. 3.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
4. 4.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
5. 5.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a magnet (d) a cotton bud
7. 7.⚖️ 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
8. 8.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) it gets darker (d) the paper floats
9. 9.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the juice scorches first (d) the iron is brown
10. 10.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) reading the message (d) dipping the cotton bud
11. 11.🛟 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
12. 12.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) ironing the paper (d) writing the message
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a balloon (c) a cotton bud (d) white paper
14. 14.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
15. 15.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
16. 16.True or false: yeast is needed for the secret lemon message. (a) False (b) True
17. 17.True or false: plugging in the iron is a job for an adult. (a) False (b) True
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a battery cell (d) a cotton bud
19. 19.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
20. 20.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a magnet (c) a balloon (d) yeast
21. 21.🍋 Which of these steps is a job a child can do? (a) writing the message (b) ironing the paper (c) cutting the lemon (d) putting the iron away
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) an adult with an iron (d) a small bowl
23. 23.⚖️ 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 change it (c) we measure it
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) lemon juice (d) a mirror
27. 27.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
28. 28.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) plugging in the iron (d) reading the message
29. 29.⚖️ 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
30. 30.True or false: putting the iron away is a job a child can do. (a) True (b) False
31. 31.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) plugging in the iron (d) reading the message
32. 32.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) blue words (d) dark brown words
33. 33.True or false: plugging in the iron is a job a child can do. (a) True (b) False
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
35. 35.True or false: putting the iron away is a job for an adult. (a) False (b) True
36. 36.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
37. 37.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) yeast (d) lemon juice
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a magnet (c) a small bowl (d) lemon juice
40. 40.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False

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