Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 480 · 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.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) the paper floats (d) writing turns green
2. 2.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
3. 3.🧺 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) a balloon (d) a cotton bud
4. 4.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) ironing the paper (d) cutting the lemon
5. 5.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
6. 6.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) whoever is fastest (d) the youngest child
7. 7.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) how dark the writing is (c) the same cotton bud (d) the kind of juice
9. 9.🧺 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) white paper (d) a magnet
10. 10.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
11. 11.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
12. 12.⚖️ 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
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same paper (c) the kind of juice (d) the same cotton bud
14. 14.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) ironing the paper (d) cutting the lemon
15. 15.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
16. 16.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) yeast (c) an adult with an iron (d) a small bowl
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) white paper (c) a small bowl (d) lemon juice
19. 19.True or false: writing the message is a job a child can do. (a) False (b) True
20. 20.⚖️ 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 keep it the same (c) we measure it
21. 21.⚖️ 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
22. 22.True or false: writing the message is a job for an adult. (a) True (b) False
23. 23.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) cutting the lemon (c) reading the message (d) writing the message
24. 24.⚖️ 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
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a small bowl (d) turmeric powder
26. 26.True or false: reading the message is a job for an adult. (a) True (b) False
27. 27.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
28. 28.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) no, it stays brown (d) yes, if shaken
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a mirror (c) a small bowl (d) white paper
30. 30.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) blue words (d) dark brown words
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
32. 32.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
33. 33.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
34. 34.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) a magnet (d) yeast
35. 35.True or false: ironing the paper is a job for an adult. (a) False (b) True
36. 36.⚖️ 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 same paper (c) the kind of juice
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a magnet (c) lemon juice (d) a small bowl
38. 38.True or false: plugging in the iron is a job for an adult. (a) True (b) False
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
40. 40.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False

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