Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 383 · 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.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) dark brown words (d) almost nothing
2. 2.⚖️ 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
3. 3.True or false: plugging in the iron is a job a child can do. (a) True (b) False
4. 4.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
5. 5.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) a cotton bud (d) turmeric powder
7. 7.⚖️ 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 ironing time (c) the iron setting (d) the kind of juice
8. 8.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
9. 9.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
10. 10.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
11. 11.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) putting the iron away (c) ironing the paper (d) cutting the lemon
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a balloon (d) yeast
13. 13.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
14. 14.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
15. 15.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
16. 16.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
17. 17.⚖️ 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
18. 18.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
19. 19.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
20. 20.⚖️ 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
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
22. 22.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) dipping the cotton bud (d) writing the message
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) white paper (d) a battery cell
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
25. 25.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
26. 26.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
27. 27.⚖️ 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
28. 28.🧺 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 mirror (d) a cotton bud
29. 29.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) lick your fingers (d) rub your eyes
30. 30.True or false: white paper is needed for the secret lemon message. (a) True (b) False
31. 31.⚖️ 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 kind of juice (c) the iron setting (d) the ironing time
32. 32.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) the juice scorches first (d) paper turns lemony
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) yeast (d) a small bowl
34. 34.True or false: writing the message is a job for an adult. (a) False (b) True
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) lemon juice (d) yeast
36. 36.True or false: letting the paper dry is a job for an adult. (a) False (b) True
37. 37.True or false: yeast is needed for the secret lemon message. (a) False (b) True
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
39. 39.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
40. 40.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True

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