Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 593 · 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 the one thing we change? (a) the iron setting (b) how dark the writing is (c) the same paper (d) the kind of juice
2. 2.⚖️ 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 keep it the same (c) we change it
3. 3.🍋 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
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) a cotton bud (d) white paper
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
7. 7.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
8. 8.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
9. 9.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
10. 10.⚖️ 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
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
12. 12.⚖️ 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
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
14. 14.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) putting the iron away (d) dipping the cotton bud
15. 15.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
16. 16.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) almost nothing (d) a rainbow
17. 17.True or false: cutting the lemon is a job for an adult. (a) True (b) False
18. 18.⚖️ 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 change it (c) we keep it the same
19. 19.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
20. 20.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) letting the paper dry (d) plugging in the iron
21. 21.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) ironing the paper
22. 22.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
23. 23.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) writing the message (d) ironing the paper
24. 24.⚖️ 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
25. 25.True or false: letting the paper dry is a job for an adult. (a) True (b) False
26. 26.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
27. 27.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
30. 30.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
31. 31.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) reading the message (d) letting the paper dry
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a balloon (c) an adult with an iron (d) white paper
33. 33.⚖️ 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
34. 34.True or false: putting the iron away is a job a child can do. (a) False (b) True
35. 35.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) the iron is brown (d) heat adds colour
36. 36.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
37. 37.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
38. 38.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
39. 39.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
40. 40.True or false: plugging in the iron is a job for an adult. (a) True (b) False

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