Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 812 · 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: yeast is not needed for the secret lemon message. (a) True (b) False
2. 2.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) reading the message (d) plugging in the iron
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a cotton bud (c) lemon juice (d) an adult with an iron
5. 5.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) cutting the lemon (d) ironing the paper
6. 6.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) putting the iron away (d) dipping the cotton bud
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a balloon (d) a small bowl
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
10. 10.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
11. 11.⚖️ 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
12. 12.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) letting the paper dry (d) ironing the paper
13. 13.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) letting the paper dry (d) cutting the lemon
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a battery cell (c) a cotton bud (d) white paper
15. 15.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
16. 16.⚖️ 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
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the iron setting (d) the ironing time
18. 18.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
19. 19.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a small bowl (c) lemon juice (d) an adult with an iron
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
22. 22.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) white (d) green
23. 23.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
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 measure it (b) we keep it the same (c) we change it
25. 25.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
26. 26.True or false: ironing the paper is a job for an adult. (a) False (b) True
27. 27.True or false: letting the paper dry is a job a child can do. (a) False (b) True
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a magnet (d) an adult with an iron
29. 29.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) ironing the paper (d) cutting the lemon
30. 30.True or false: plugging in the iron is a job a child can do. (a) False (b) True
31. 31.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
32. 32.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
33. 33.True or false: reading the message is a job for an adult. (a) False (b) True
34. 34.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
35. 35.⚖️ 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
36. 36.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) a balloon (d) an adult with an iron
37. 37.⚖️ 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 ironing time
38. 38.🔮 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
39. 39.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
40. 40.⚖️ 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) how dark the writing is (c) the ironing time

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