Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 448 · 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 does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
2. 2.True or false: letting the paper dry is a job for an adult. (a) False (b) True
3. 3.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) turmeric powder (d) a small bowl
4. 4.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) a small bowl (d) a battery cell
6. 6.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
7. 7.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
8. 8.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) cutting the lemon
9. 9.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) dipping the cotton bud
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) a battery cell (d) white paper
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) turmeric powder (d) white paper
12. 12.⚖️ 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 same paper
13. 13.🛟 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
14. 14.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a magnet (d) a battery cell
15. 15.⚖️ 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
16. 16.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) the paper ate it (d) it turned into air
17. 17.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) reading the message (d) plugging in the iron
18. 18.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) writing the message
19. 19.🍋 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) dipping the cotton bud
20. 20.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
21. 21.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
22. 22.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
23. 23.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) the paper floats (d) writing turns green
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.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) a cotton bud (c) an adult with an iron (d) white paper
26. 26.True or false: cutting the lemon is a job for an adult. (a) False (b) True
27. 27.⚖️ 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 change it (c) we keep it the same
28. 28.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) a battery cell (d) a magnet
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the iron setting (c) how dark the writing is (d) the same paper
30. 30.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
31. 31.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
32. 32.True or false: writing the message is a job for an adult. (a) False (b) True
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) a balloon (d) white paper
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) a small bowl (d) a cotton bud
35. 35.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) letting the paper dry
36. 36.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
37. 37.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) dark brown words (d) a rainbow
38. 38.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
40. 40.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False

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