Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 702 · 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.🧺 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) lemon juice
2. 2.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
3. 3.True or false: letting the paper dry is a job for an adult. (a) True (b) False
4. 4.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
5. 5.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
6. 6.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
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 ironing time (b) how dark the writing is (c) the kind of juice (d) the same paper
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a cotton bud (c) a balloon (d) yeast
9. 9.⚖️ 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) False (b) True
10. 10.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
12. 12.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a small bowl (d) a balloon
14. 14.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a cotton bud (c) white paper (d) a small bowl
16. 16.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
17. 17.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) an adult with an iron (d) turmeric powder
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) white paper (d) a cotton bud
19. 19.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) lemon juice (d) a mirror
21. 21.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
22. 22.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) paper turns lemony (d) the juice scorches first
23. 23.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
24. 24.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
25. 25.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) yeast (c) lemon juice (d) a cotton bud
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) turmeric powder (d) a small bowl
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.⚖️ 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
30. 30.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) white paper (d) a battery cell
31. 31.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, in the dark (d) yes, if shaken
32. 32.🍋 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
33. 33.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) dipping the cotton bud (d) letting the paper dry
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) lemon juice (d) a balloon
35. 35.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) reading the message (d) writing the message
36. 36.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) reading the message (d) letting the paper dry
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
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 keep it the same (c) we measure it
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
40. 40.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False

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