Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 55 · 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) putting the iron away (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
2. 2.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
3. 3.🔮 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
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) yeast (c) lemon juice (d) white paper
5. 5.⚖️ 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
6. 6.True or false: letting the paper dry is a job for an adult. (a) False (b) True
7. 7.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
8. 8.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) ironing the paper (d) plugging in the iron
9. 9.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is cold (d) it is magnetic
10. 10.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
11. 11.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a balloon (c) a mirror (d) a battery cell
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a cotton bud (d) a mirror
13. 13.True or false: cutting the lemon is a job a child can do. (a) True (b) False
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) white paper (d) a battery cell
15. 15.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a balloon (c) a mirror (d) yeast
16. 16.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
17. 17.🍋 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
18. 18.⚖️ 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
19. 19.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
20. 20.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
23. 23.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) writing the message
24. 24.⚖️ 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 kind of juice (c) the ironing time
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
26. 26.🔍 Which is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) putting the iron away (d) plugging in the iron
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a magnet (c) an adult with an iron (d) a cotton bud
28. 28.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
29. 29.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
30. 30.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) white paper (c) a battery cell (d) a magnet
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
32. 32.⚖️ 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
33. 33.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
34. 34.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) putting the iron away (d) writing the message
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a cotton bud (d) turmeric powder
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
38. 38.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
40. 40.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest

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