Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 910 · 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.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
2. 2.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
4. 4.True or false: white paper is needed for the secret lemon message. (a) True (b) False
5. 5.True or false: cutting the lemon is a job a child can do. (a) False (b) True
6. 6.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is sticky (d) it is magnetic
7. 7.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) white paper (d) yeast
10. 10.⚖️ 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) how dark the writing is (c) the ironing time (d) the kind of juice
11. 11.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same paper (c) how dark the writing is
13. 13.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) no, it stays brown (d) yes, in the dark
14. 14.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) cutting the lemon (d) plugging in the iron
15. 15.⚖️ 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
16. 16.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) letting the paper dry (c) reading the message (d) dipping the cotton bud
17. 17.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) putting the iron away (c) letting the paper dry (d) reading the message
18. 18.⚖️ 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 iron setting (c) the same cotton bud (d) the kind of juice
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
21. 21.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
22. 22.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) writing the message
23. 23.🧺 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) a magnet
24. 24.⚖️ 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
25. 25.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
27. 27.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
28. 28.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
29. 29.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
30. 30.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) plugging in the iron
31. 31.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) ironing the paper
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) turmeric powder (d) a cotton bud
33. 33.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
34. 34.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
35. 35.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) letting the paper dry (d) putting the iron away
36. 36.True or false: letting the paper dry is a job a child can do. (a) False (b) True
37. 37.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) lemon juice (c) a magnet (d) yeast
38. 38.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) an adult with an iron (d) white paper
40. 40.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed

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