Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 994 · 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.⚖️ 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
2. 2.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
3. 3.True or false: yeast is needed for the secret lemon message. (a) True (b) False
4. 4.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) a small bowl (d) a magnet
5. 5.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) it turned into air (d) the ink is magnetic
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
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 ironing time (b) the kind of juice (c) how dark the writing is (d) the same paper
8. 8.True or false: cutting the lemon is a job for an adult. (a) False (b) True
9. 9.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) any child (d) only an adult
11. 11.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
12. 12.⚖️ 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
13. 13.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
14. 14.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a cotton bud (d) white paper
16. 16.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) a rainbow (d) blue words
17. 17.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) heat adds colour (c) paper turns lemony (d) the iron is brown
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a cotton bud (c) an adult with an iron (d) a small bowl
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a small bowl (c) a cotton bud (d) white paper
20. 20.⚖️ 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 change it (c) we measure it
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
22. 22.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it can burn skin (d) it is magnetic
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a small bowl (c) a cotton bud (d) an adult with an iron
24. 24.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a battery cell (c) a cotton bud (d) lemon juice
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
27. 27.⚖️ 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
28. 28.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
29. 29.True or false: letting the paper dry is a job a child can do. (a) False (b) True
30. 30.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
31. 31.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
32. 32.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
33. 33.True or false: plugging in the iron is a job a child can do. (a) False (b) True
34. 34.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
35. 35.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) ironing the paper (d) letting the paper dry
36. 36.⚖️ 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
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a mirror (c) white paper (d) a cotton bud
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the ironing time (d) the same paper
39. 39.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a cotton bud (c) white paper (d) a small bowl

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