Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 832 · 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.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
2. 2.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) cutting the lemon
3. 3.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) an adult with an iron (d) a small bowl
5. 5.⚖️ 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) False (b) True
6. 6.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) cutting the lemon (d) plugging in the iron
7. 7.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a mirror (c) a magnet (d) a balloon
8. 8.True or false: cutting the lemon is a job for an adult. (a) False (b) True
9. 9.True or false: ironing the paper is a job a child can do. (a) True (b) False
10. 10.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
11. 11.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) reading the message
12. 12.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) a cotton bud (d) an adult with an iron
14. 14.⚖️ 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 same paper (c) the same cotton bud (d) the kind of juice
15. 15.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) an adult with an iron (d) white paper
17. 17.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) heat adds colour (d) paper turns lemony
18. 18.⚖️ 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 ironing time (c) the kind of juice
19. 19.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
20. 20.⚖️ 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 same paper (d) the ironing time
21. 21.🧺 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
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a balloon (d) a mirror
23. 23.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
25. 25.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a cotton bud (d) a balloon
26. 26.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
27. 27.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
28. 28.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) a mirror (d) a battery cell
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
31. 31.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) any child (d) the youngest child
32. 32.⚖️ 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
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
34. 34.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
35. 35.🔮 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
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
37. 37.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
38. 38.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
39. 39.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) a cotton bud (c) a small bowl (d) lemon juice

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