Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 627 · 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) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) reading the message
2. 2.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) an adult with an iron (d) a cotton bud
4. 4.⚖️ 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 iron setting (c) the kind of juice (d) how dark the writing is
5. 5.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) white paper (d) a battery cell
6. 6.⚖️ 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 keep it the same (c) we measure it
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
8. 8.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) dipping the cotton bud
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a small bowl (d) a mirror
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) a small bowl (d) turmeric powder
11. 11.True or false: reading the message is a job a child can do. (a) False (b) True
12. 12.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) dipping the cotton bud
13. 13.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) cutting the lemon
14. 14.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
15. 15.⚖️ 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 same cotton bud (c) how dark the writing is
16. 16.True or false: putting the iron away is a job for an adult. (a) False (b) True
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) yeast (d) an adult with an iron
18. 18.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
19. 19.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) dark brown words (d) a rainbow
20. 20.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
21. 21.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a balloon (c) an adult with an iron (d) a cotton bud
23. 23.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
24. 24.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
25. 25.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) lemon juice (d) a balloon
26. 26.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
27. 27.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the juice scorches first (d) the iron is brown
28. 28.🔮 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
29. 29.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) putting the iron away (d) letting the paper dry
30. 30.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
31. 31.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
32. 32.⚖️ 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 change it (c) we keep it the same
33. 33.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
34. 34.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
35. 35.🧺 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 battery cell (d) lemon juice
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) a balloon (d) a battery cell
37. 37.⚖️ 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
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
39. 39.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) writing the message (d) ironing the paper
40. 40.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed

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