Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 116 · 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.🔮 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
2. 2.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) putting the iron away
3. 3.⚖️ 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
4. 4.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a small bowl (c) turmeric powder (d) yeast
6. 6.⚖️ 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
7. 7.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
9. 9.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) white (d) blue
10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) whoever is fastest (d) any child
11. 11.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) plugging in the iron (d) cutting the lemon
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a small bowl (d) yeast
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) an adult with an iron (d) turmeric powder
14. 14.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
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.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
17. 17.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
18. 18.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the kind of juice (c) the same paper (d) how dark the writing is
20. 20.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
21. 21.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
22. 22.⚖️ 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
23. 23.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
24. 24.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a magnet (c) a battery cell (d) a mirror
25. 25.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) an adult with an iron (c) a small bowl (d) lemon juice
27. 27.⚖️ 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 measure it (c) we change it
28. 28.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
29. 29.True or false: writing the message is a job for an adult. (a) True (b) False
30. 30.🍋 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
31. 31.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
32. 32.⚖️ 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 measure it (c) we keep it the same
33. 33.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) dipping the cotton bud (d) writing the message
34. 34.True or false: plugging in the iron is a job for an adult. (a) True (b) False
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a cotton bud (d) a battery cell
36. 36.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
37. 37.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) letting the paper dry (d) ironing the paper
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) an adult with an iron (c) a cotton bud (d) lemon juice
39. 39.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
40. 40.True or false: letting the paper dry is a job for an adult. (a) True (b) False

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