Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 412 · 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 magnet for the secret lemon message? (a) not needed (b) needed
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the same paper (d) the iron setting
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) an adult with an iron (d) a cotton bud
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) lemon juice (c) yeast (d) a magnet
5. 5.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a magnet (d) a small bowl
6. 6.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
7. 7.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words
8. 8.🍋 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
9. 9.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
10. 10.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
11. 11.True or false: putting the iron away is a job a child can do. (a) True (b) False
12. 12.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
13. 13.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a cotton bud (c) white paper (d) lemon juice
15. 15.⚖️ 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
16. 16.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
17. 17.🛟 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
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) yeast (d) a cotton bud
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) an adult with an iron (d) a magnet
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a mirror (c) lemon juice (d) a cotton bud
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) an adult with an iron (c) white paper (d) a cotton bud
22. 22.True or false: reading the message is a job for an adult. (a) False (b) True
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the ironing time (c) the kind of juice (d) how dark the writing is
24. 24.True or false: white paper is needed for the secret lemon message. (a) True (b) False
25. 25.⚖️ 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
26. 26.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a mirror (c) a battery cell (d) a balloon
27. 27.True or false: plugging in the iron is a job a child can do. (a) True (b) False
28. 28.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
29. 29.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) dipping the cotton bud (d) letting the paper dry
30. 30.⚖️ 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
31. 31.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
32. 32.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) dipping the cotton bud (d) ironing the paper
33. 33.⚖️ 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
34. 34.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a mirror (d) a cotton bud
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
37. 37.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) paper turns lemony (d) heat adds colour
38. 38.🍋 Secret message: who does this step — putting the iron away? (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? True or false: the iron setting is what we measure. (a) False (b) True
40. 40.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) dipping the cotton bud

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