Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 299 · 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) letting the paper dry (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
2. 2.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) ironing the paper
3. 3.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
4. 4.⚖️ 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
5. 5.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) reading the message (c) dipping the cotton bud (d) letting the paper dry
6. 6.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) writing the message (c) dipping the cotton bud (d) reading the message
7. 7.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
8. 8.⚖️ 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
9. 9.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) an adult with an iron (c) a magnet (d) turmeric powder
10. 10.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
11. 11.⚖️ 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 keep it the same (c) we change it
12. 12.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
13. 13.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
14. 14.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) how dark the writing is (c) the same paper (d) the ironing time
16. 16.⚖️ 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
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a cotton bud (d) white paper
18. 18.True or false: ironing the paper is a job for an adult. (a) True (b) False
19. 19.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
20. 20.⚖️ 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
21. 21.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) letting the paper dry (d) dipping the cotton bud
22. 22.True or false: cutting the lemon is a job a child can do. (a) False (b) True
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
24. 24.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) putting the iron away (d) ironing the paper
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) white paper (c) lemon juice (d) a small bowl
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the same paper (c) how dark the writing is (d) the kind of juice
27. 27.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) writing the message (d) cutting the lemon
28. 28.True or false: plugging in the iron is a job a child can do. (a) True (b) False
29. 29.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
31. 31.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) whoever is fastest (d) any child
32. 32.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
33. 33.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) heat adds colour (c) the iron is brown (d) paper turns lemony
34. 34.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
35. 35.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) white paper (d) a magnet
37. 37.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
38. 38.⚖️ 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
39. 39.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) a cotton bud (d) lemon juice

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