Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 560 · 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.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) writing the message (d) cutting the lemon
2. 2.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) blue (d) green
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) an adult with an iron (d) a battery cell
4. 4.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
5. 5.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) ironing the paper (d) plugging in the iron
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) an adult with an iron (c) lemon juice (d) white paper
7. 7.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
8. 8.True or false: letting the paper dry is a job for an adult. (a) True (b) False
9. 9.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) an adult with an iron (d) lemon juice
11. 11.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) white paper (c) lemon juice (d) a small bowl
13. 13.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
14. 14.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
15. 15.🍋 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) writing the message
16. 16.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
17. 17.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) a magnet (d) an adult with an iron
18. 18.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) cutting the lemon
19. 19.True or false: ironing the paper is a job for an adult. (a) True (b) False
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) yeast (d) a small bowl
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) a small bowl (d) lemon juice
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) a mirror (d) turmeric powder
23. 23.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) the iron is brown (d) heat adds colour
24. 24.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
25. 25.True or false: reading the message is a job a child can do. (a) True (b) False
26. 26.🍋 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
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
28. 28.⚖️ 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) True (b) False
29. 29.True or false: letting the paper dry is a job a child can do. (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.⚖️ 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
32. 32.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
33. 33.⚖️ 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 measure it (c) we keep it the same
34. 34.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
35. 35.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) a cotton bud (d) white paper
37. 37.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
38. 38.True or false: cutting the lemon is a job for an adult. (a) True (b) False
39. 39.⚖️ 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
40. 40.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed

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