Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 401 · 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.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) cutting the lemon (d) dipping the cotton bud
2. 2.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) a magnet (d) a cotton bud
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) a cotton bud (d) white paper
4. 4.⚖️ 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) the same cotton bud (c) the ironing time (d) the kind of juice
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) a small bowl (d) white paper
7. 7.True or false: putting the iron away is a job a child can do. (a) True (b) False
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a battery cell (d) yeast
9. 9.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) letting the paper dry (d) cutting the lemon
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) white paper (d) a small bowl
11. 11.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
12. 12.True or false: plugging in the iron is a job a child can do. (a) True (b) False
13. 13.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) green (d) white
14. 14.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) a magnet (d) an adult with an iron
15. 15.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, if shaken (d) yes, in the dark
16. 16.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
17. 17.True or false: white paper is needed for the secret lemon message. (a) False (b) True
18. 18.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
19. 19.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
21. 21.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
22. 22.⚖️ 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
23. 23.🍋 Which of these steps is a job a child can do? (a) reading the message (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
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.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
26. 26.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
27. 27.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) plugging in the iron (d) cutting the lemon
28. 28.True or false: cutting the lemon is a job a child can do. (a) True (b) False
29. 29.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
31. 31.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) turmeric powder (c) a small bowl (d) lemon juice
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) turmeric powder (d) a small bowl
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
35. 35.⚖️ 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
36. 36.⚖️ 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
37. 37.True or false: ironing the paper is a job for an adult. (a) True (b) False
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) an adult with an iron (d) a balloon
39. 39.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) letting the paper dry
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False

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