Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 958 · 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.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the paper ate it (d) the ink is magnetic
2. 2.True or false: writing the message is a job for an adult. (a) True (b) False
3. 3.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
4. 4.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
5. 5.🍋 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
6. 6.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) blue words (d) dark brown words
7. 7.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
8. 8.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) writing the message
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) an adult with an iron (d) a cotton bud
10. 10.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it can burn skin (d) it is cold
11. 11.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
12. 12.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) ironing the paper (d) cutting the lemon
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) a battery cell (d) lemon juice
14. 14.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) cutting the lemon (d) letting the paper dry
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a small bowl (c) a balloon (d) a magnet
16. 16.True or false: an adult with an iron 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? Which of these is the one thing we change? (a) the iron setting (b) the ironing time (c) the kind of juice (d) the same paper
18. 18.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
19. 19.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) dipping the cotton bud (c) writing the message (d) reading the message
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 measure it (c) we change it
21. 21.⚖️ 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) the same paper (c) how dark the writing is
22. 22.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) putting the iron away (d) letting the paper dry
23. 23.⚖️ 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 cotton bud (c) how dark the writing is (d) the kind of juice
24. 24.True or false: writing the message is a job a child can do. (a) True (b) False
25. 25.🍋 Which of these steps is a job a child can do? (a) writing the message (b) ironing the paper (c) plugging in the iron (d) cutting the lemon
26. 26.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) plugging in the iron
27. 27.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
28. 28.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
29. 29.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a mirror (d) white paper
30. 30.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) letting the paper dry
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
32. 32.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a magnet (d) a cotton bud
33. 33.True or false: letting the paper dry is a job a child can do. (a) True (b) False
34. 34.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) white paper (d) a balloon
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) a small bowl (d) an adult with an iron
37. 37.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
38. 38.🧺 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) lemon juice (d) a magnet
39. 39.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
40. 40.🧺 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 small bowl (d) a balloon

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