Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 274 · 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.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) ironing the paper (d) dipping the cotton bud
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a cotton bud (c) white paper (d) lemon juice
3. 3.🍋 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
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) a balloon (d) white paper
5. 5.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
6. 6.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) putting the iron away (d) letting the paper dry
7. 7.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) ironing the paper (c) letting the paper dry (d) reading the message
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) a magnet (d) an adult with an iron
9. 9.⚖️ 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 keep it the same (c) we change it
10. 10.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) reading the message (d) ironing the paper
11. 11.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
12. 12.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) writing turns green (d) it gets darker
13. 13.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
14. 14.⚖️ 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
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) lemon juice (d) yeast
16. 16.⚖️ 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 kind of juice (c) the ironing time (d) how dark the writing is
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same cotton bud (c) the ironing time (d) the iron setting
18. 18.True or false: reading the message is a job a child can do. (a) True (b) False
19. 19.True or false: cutting the lemon is a job for an adult. (a) True (b) False
20. 20.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) physical (d) chemical
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
22. 22.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) plugging in the iron
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a magnet (d) a small bowl
24. 24.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
25. 25.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
26. 26.⚖️ 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
27. 27.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) green (d) white
28. 28.⚖️ 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
29. 29.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
30. 30.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) a rainbow (d) dark brown words
31. 31.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) a small bowl (d) a battery cell
32. 32.True or false: writing the message is a job for an adult. (a) False (b) True
33. 33.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) writing the message (d) reading the message
34. 34.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) paper turns lemony (d) the juice scorches first
35. 35.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
36. 36.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
37. 37.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
38. 38.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
39. 39.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
40. 40.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it

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