Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 257 · 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: dipping the cotton bud is a job for an adult. (a) False (b) True
2. 2.🍋 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
3. 3.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
4. 4.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
6. 6.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) a cotton bud (d) a small bowl
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) an adult with an iron (c) a small bowl (d) lemon juice
9. 9.🛟 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
10. 10.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) writing the message (d) putting the iron away
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the same paper
12. 12.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
13. 13.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
14. 14.🧺 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
15. 15.⚖️ 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) True (b) False
16. 16.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) writing the message
17. 17.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) an adult with an iron (d) a balloon
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the kind of juice (c) the ironing time (d) the iron setting
19. 19.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) ironing the paper
20. 20.🔮 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
21. 21.⚖️ 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
22. 22.True or false: letting the paper dry is a job for an adult. (a) True (b) False
23. 23.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
24. 24.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
25. 25.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
26. 26.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) ironing the paper
27. 27.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
28. 28.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
29. 29.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
30. 30.⚖️ 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 change it (c) we measure it
31. 31.True or false: ironing the paper is a job for an adult. (a) True (b) False
32. 32.True or false: writing the message is a job a child can do. (a) False (b) True
33. 33.True or false: plugging in the iron is a job a child can do. (a) False (b) True
34. 34.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) turmeric powder (d) white paper
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
37. 37.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
38. 38.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) dipping the cotton bud (d) cutting the lemon
39. 39.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
40. 40.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) reading the message (d) cutting the lemon

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