Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 239 · 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 of these is needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) a magnet (d) a battery cell
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the same paper
3. 3.True or false: cutting the lemon is a job a child can do. (a) False (b) True
4. 4.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a mirror (d) turmeric powder
7. 7.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) writing turns green (d) it gets darker
8. 8.True or false: plugging in the iron is a job a child can do. (a) False (b) True
9. 9.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) white (d) blue
10. 10.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
11. 11.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
13. 13.🧺 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) an adult with an iron
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) an adult with an iron (c) a cotton bud (d) a small bowl
15. 15.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
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 iron setting (b) the ironing time (c) the kind of juice (d) the same cotton bud
17. 17.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) writing the message (d) reading the message
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a balloon (d) a cotton bud
19. 19.⚖️ 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
20. 20.🔍 Which is the odd one out? (a) letting the paper dry (b) putting the iron away (c) cutting the lemon (d) plugging in the iron
21. 21.True or false: ironing the paper is a job for an adult. (a) False (b) True
22. 22.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
23. 23.🔮 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
24. 24.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a cotton bud (d) a balloon
26. 26.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) plugging in the iron (d) cutting the lemon
27. 27.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it can burn skin (d) it is sticky
28. 28.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) reading the message (d) writing the message
29. 29.True or false: plugging in the iron is a job for an adult. (a) False (b) True
30. 30.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
31. 31.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
33. 33.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
34. 34.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a small bowl (d) a magnet
36. 36.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) heat adds colour (d) the iron is brown
37. 37.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) white paper (d) a balloon
38. 38.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
39. 39.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
40. 40.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) cutting the lemon

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