Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 930 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a cotton bud (d) yeast
2. 2.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) white paper (c) a battery cell (d) yeast
3. 3.True or false: letting the paper dry is a job a child can do. (a) False (b) True
4. 4.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
5. 5.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
6. 6.True or false: ironing the paper is a job a child can do. (a) True (b) False
7. 7.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
9. 9.🔮 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
10. 10.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) cutting the lemon (d) writing the message
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) a balloon (d) an adult with an iron
12. 12.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
13. 13.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) ironing the paper (d) letting the paper dry
14. 14.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
15. 15.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
16. 16.⚖️ 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
17. 17.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
18. 18.⚖️ 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
19. 19.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) ironing the paper
20. 20.True or false: putting the iron away is a job a child can do. (a) False (b) True
21. 21.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) white (d) green
22. 22.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) the paper ate it (d) it turned into air
23. 23.True or false: cutting the lemon is a job a child can do. (a) True (b) False
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) lemon juice (d) white paper
25. 25.⚖️ 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
26. 26.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
27. 27.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
28. 28.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
29. 29.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
30. 30.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the iron is brown (d) the juice scorches first
31. 31.⚖️ 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
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
34. 34.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
35. 35.⚖️ 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
36. 36.🍋 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) reading the message
37. 37.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) white paper (d) lemon juice
39. 39.⚖️ 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 iron setting (c) how dark the writing is (d) the kind of juice
40. 40.True or false: yeast is needed for the secret lemon message. (a) True (b) False

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