Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 142 · 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.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
2. 2.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) a rainbow (d) dark brown words
3. 3.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a balloon (d) a mirror
4. 4.⚖️ 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
5. 5.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
6. 6.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) plugging in the iron (d) letting the paper dry
7. 7.⚖️ 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
8. 8.True or false: writing the message is a job a child can do. (a) False (b) True
9. 9.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) dipping the cotton bud (d) reading the message
10. 10.True or false: ironing the paper is a job a child can do. (a) True (b) False
11. 11.True or false: yeast is needed for the secret lemon message. (a) True (b) False
12. 12.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
13. 13.⚖️ 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 change it (c) we keep it the same
14. 14.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the ink is magnetic (d) the paper ate it
15. 15.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it can burn skin (d) it is cold
16. 16.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
17. 17.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
18. 18.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
19. 19.⚖️ 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 cotton bud (c) how dark the writing is
20. 20.True or false: cutting the lemon is a job a child can do. (a) False (b) True
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a mirror (d) a cotton bud
22. 22.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
23. 23.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) letting the paper dry (d) writing the message
24. 24.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) reading the message (d) cutting the lemon
25. 25.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) rub your eyes (d) lick your fingers
26. 26.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) white paper (c) an adult with an iron (d) lemon juice
28. 28.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) writing the message (d) plugging in the iron
29. 29.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a mirror (c) yeast (d) a balloon
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
31. 31.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) dipping the cotton bud (d) putting the iron away
32. 32.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
34. 34.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a battery cell (d) white paper
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a small bowl (d) a magnet
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
38. 38.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
39. 39.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
40. 40.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed

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