Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 12 · 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.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
2. 2.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) plugging in the iron (d) ironing the paper
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) an adult with an iron (c) white paper (d) a small bowl
4. 4.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) turmeric powder (d) a small bowl
5. 5.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
6. 6.⚖️ 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
7. 7.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) the iron is brown (d) heat adds colour
8. 8.🧺 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 battery cell
9. 9.⚖️ 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
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
11. 11.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if cooled (d) yes, if shaken
12. 12.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) reading the message (d) ironing the paper
13. 13.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
14. 14.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
15. 15.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
16. 16.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
17. 17.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
18. 18.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) lemon juice (d) a magnet
20. 20.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) white paper (d) a cotton bud
22. 22.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
23. 23.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) cutting the lemon
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
25. 25.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
26. 26.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) the paper floats (d) writing stays faint
27. 27.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
28. 28.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) putting the iron away
29. 29.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
30. 30.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) plugging in the iron (d) putting the iron away
31. 31.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) a mirror (d) a magnet
32. 32.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the same cotton bud (c) the ironing time (d) how dark the writing is
34. 34.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
36. 36.⚖️ 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
37. 37.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
38. 38.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
39. 39.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) writing the message (d) dipping the cotton bud
40. 40.True or false: ironing the paper is a job for an adult. (a) False (b) True

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