Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 676 · 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 can burn skin (b) it is magnetic (c) it is sticky (d) it is cold
2. 2.⚖️ 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 measure it (c) we keep it the same
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) an adult with an iron (d) a balloon
4. 4.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) paper turns lemony (d) the iron is brown
5. 5.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
6. 6.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) lemon juice (d) yeast
8. 8.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) dipping the cotton bud (d) ironing the paper
9. 9.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a magnet (c) turmeric powder (d) a balloon
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) white paper (c) an adult with an iron (d) lemon juice
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) an adult with an iron (c) a cotton bud (d) white paper
12. 12.True or false: plugging in the iron is a job for an adult. (a) True (b) False
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a mirror (d) a cotton bud
15. 15.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
16. 16.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) a magnet (d) an adult with an iron
18. 18.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
20. 20.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) dipping the cotton bud (d) writing the message
21. 21.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
23. 23.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) writing turns green (d) the paper floats
24. 24.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
25. 25.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
26. 26.True or false: reading the message is a job for an adult. (a) False (b) True
27. 27.True or false: cutting the lemon is a job a child can do. (a) True (b) False
28. 28.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
29. 29.⚖️ 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
30. 30.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) reading the message (d) dipping the cotton bud
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) white paper (d) a balloon
32. 32.⚖️ 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) how dark the writing is (c) the ironing time
33. 33.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) ironing the paper
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the same paper (c) how dark the writing is (d) the iron setting
35. 35.⚖️ 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 same cotton bud (c) how dark the writing is (d) the kind of juice
36. 36.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
37. 37.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) plugging in the iron (d) dipping the cotton bud
38. 38.True or false: cutting the lemon is a job for an adult. (a) True (b) False
39. 39.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) reading the message (c) writing the message (d) letting the paper dry
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) white paper (d) a battery cell

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