Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 920 · 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: putting the iron away is a job a child can do. (a) True (b) False
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) lemon juice (c) white paper (d) an adult with an iron
3. 3.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
4. 4.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) a small bowl (d) a magnet
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a small bowl (c) a cotton bud (d) lemon juice
7. 7.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) yeast (c) a cotton bud (d) an adult with an iron
10. 10.True or false: putting the iron away is a job for an adult. (a) False (b) True
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) an adult with an iron (d) white paper
12. 12.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
13. 13.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
14. 14.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
15. 15.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a small bowl (d) a magnet
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
18. 18.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
19. 19.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) dipping the cotton bud (c) reading the message (d) writing the message
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) almost nothing (d) blue words
21. 21.True or false: letting the paper dry is a job for an adult. (a) True (b) False
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) yeast (d) a magnet
23. 23.⚖️ 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
24. 24.⚖️ 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 measure it (c) we change it
25. 25.⚖️ 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 same cotton bud (d) the kind of juice
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) yeast (d) white paper
27. 27.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
28. 28.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
29. 29.True or false: writing the message is a job a child can do. (a) False (b) True
30. 30.🍋 Which of these steps is a job a child can do? (a) writing the message (b) cutting the lemon (c) ironing the paper (d) putting the iron away
31. 31.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
32. 32.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) putting the iron away
33. 33.⚖️ 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) True (b) False
34. 34.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical
35. 35.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) an adult with an iron (d) a mirror
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) a battery cell (d) yeast
39. 39.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) dry juice is see-through (d) the ink is magnetic
40. 40.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) putting the iron away (d) cutting the lemon

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