Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 502 · 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.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) it gets darker (d) writing turns green
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) yeast (d) a small bowl
4. 4.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
5. 5.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) white paper (d) a mirror
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) lemon juice (c) a small bowl (d) an adult with an iron
7. 7.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
8. 8.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) dipping the cotton bud
9. 9.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
10. 10.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) letting the paper dry
11. 11.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) letting the paper dry
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a magnet (d) white paper
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
14. 14.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a cotton bud (d) a mirror
15. 15.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) white paper (d) a battery cell
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the iron setting (c) the ironing time (d) the kind of juice
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
19. 19.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is magnetic (d) it is sticky
20. 20.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
21. 21.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
22. 22.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
23. 23.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
24. 24.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) putting the iron away
25. 25.True or false: ironing the paper is a job a child can do. (a) False (b) True
26. 26.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
27. 27.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) a small bowl (d) a cotton bud
29. 29.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) cutting the lemon (d) dipping the cotton bud
30. 30.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) writing the message (d) dipping the cotton bud
31. 31.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) cutting the lemon (d) plugging in the iron
32. 32.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
33. 33.True or false: letting the paper dry is a job for an adult. (a) True (b) False
34. 34.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
35. 35.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) the juice scorches first (d) paper turns lemony
36. 36.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) putting the iron away (d) dipping the cotton bud
37. 37.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
38. 38.⚖️ 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
39. 39.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) ironing the paper (d) reading the message
40. 40.True or false: writing the message is a job a child can do. (a) False (b) True

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