Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 350 · 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 cotton bud for the secret lemon message? (a) not needed (b) needed
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) the youngest child (d) any child
3. 3.⚖️ 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 change it (c) we measure it
4. 4.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) letting the paper dry (d) dipping the cotton bud
5. 5.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
6. 6.⚖️ 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) how dark the writing is (c) the ironing time
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) a cotton bud (d) an adult with an iron
8. 8.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
9. 9.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
10. 10.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the iron is brown (d) the juice scorches first
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) turmeric powder (d) a cotton bud
12. 12.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
13. 13.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
14. 14.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) a small bowl (d) an adult with an iron
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a magnet (d) an adult with an iron
17. 17.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
18. 18.True or false: reading the message is a job a child can do. (a) False (b) True
19. 19.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) plugging in the iron (d) cutting the lemon
20. 20.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
21. 21.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
22. 22.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green
23. 23.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) putting the iron away
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) lemon juice (d) a magnet
26. 26.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
27. 27.True or false: letting the paper dry is a job for an adult. (a) False (b) True
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) a battery cell (d) yeast
29. 29.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
30. 30.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
31. 31.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) dipping the cotton bud (c) plugging in the iron (d) cutting the lemon
32. 32.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) ironing the paper
33. 33.⚖️ 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
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
35. 35.True or false: cutting the lemon is a job for an adult. (a) False (b) True
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) an adult with an iron (d) white paper
37. 37.⚖️ 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) how dark the writing is (c) the iron setting (d) the kind of juice
38. 38.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
39. 39.⚖️ 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) how dark the writing is (c) the same paper
40. 40.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) turmeric powder (d) a battery cell

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