Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 773 · 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 yeast for the secret lemon message? (a) needed (b) not needed
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
3. 3.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
4. 4.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
5. 5.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
6. 6.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it is magnetic (d) it can burn skin
7. 7.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) the juice scorches first (d) heat adds colour
8. 8.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
10. 10.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical
11. 11.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled
12. 12.🧺 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) lemon juice (d) turmeric powder
13. 13.⚖️ 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) the ironing time (c) how dark the writing is
14. 14.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a magnet (d) a cotton bud
16. 16.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a magnet (c) a balloon (d) a mirror
17. 17.True or false: cutting the lemon is a job a child can do. (a) False (b) True
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) a small bowl (d) a balloon
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) a battery cell (d) an adult with an iron
21. 21.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
22. 22.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) reading the message (d) dipping the cotton bud
23. 23.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) dipping the cotton bud
24. 24.⚖️ 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 change it (c) we keep it the same
25. 25.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) it gets darker (d) the paper floats
26. 26.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
27. 27.⚖️ 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 keep it the same (c) we change it
28. 28.🧺 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 cotton bud (d) a battery cell
29. 29.🧺 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) a balloon (d) a small bowl
30. 30.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
31. 31.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
32. 32.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) cutting the lemon
33. 33.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) plugging in the iron
34. 34.⚖️ 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
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a cotton bud (d) turmeric powder
36. 36.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
37. 37.🧺 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) a magnet (d) a small bowl
38. 38.🍋 Secret message: who does this step — reading the message? (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? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the iron setting (d) the same paper
40. 40.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it

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