Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 371 · 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 kind of juice (b) the same paper (c) how dark the writing is
2. 2.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) blue (d) green
3. 3.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
4. 4.⚖️ 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 measure it (c) we change it
5. 5.⚖️ 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
6. 6.⚖️ 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 measure it (c) we change it
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) a small bowl (d) white paper
8. 8.True or false: cutting the lemon is a job a child can do. (a) False (b) True
9. 9.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) reading the message (c) ironing the paper (d) cutting the lemon
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
11. 11.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
12. 12.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) magnetic (d) musical
13. 13.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
14. 14.True or false: white paper is needed for the secret lemon message. (a) False (b) True
15. 15.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
16. 16.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
17. 17.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a mirror (c) a battery cell (d) yeast
18. 18.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
19. 19.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) writing the message
20. 20.True or false: yeast is needed for the secret lemon message. (a) True (b) False
21. 21.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
22. 22.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
23. 23.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
24. 24.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) a magnet (d) turmeric powder
25. 25.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
26. 26.🧺 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) white paper (d) a battery cell
27. 27.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) a cotton bud (d) turmeric powder
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 is the odd one out? (a) ironing the paper (b) writing the message (c) plugging in the iron (d) cutting the lemon
31. 31.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
32. 32.⚖️ 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 same paper (c) the kind of juice (d) the same cotton bud
33. 33.🛟 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
34. 34.⚖️ 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
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) a mirror
36. 36.🍋 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) dipping the cotton bud
37. 37.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
38. 38.True or false: putting the iron away is a job a child can do. (a) True (b) False
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) an adult with an iron (d) yeast

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