Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 277 · 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 — reading the message? (a) an adult does it (b) a child can do it
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) a small bowl (d) a cotton bud
3. 3.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) an adult with an iron (d) a balloon
4. 4.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) a cotton bud (d) lemon juice
6. 6.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) the paper floats (d) writing turns green
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
8. 8.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
9. 9.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
10. 10.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
11. 11.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
12. 12.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
13. 13.True or false: cutting the lemon is a job a child can do. (a) False (b) True
14. 14.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) turmeric powder (d) a cotton bud
16. 16.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) dipping the cotton bud
17. 17.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
18. 18.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
19. 19.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
20. 20.🧺 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 magnet (d) a cotton bud
21. 21.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) a rainbow (d) dark brown words
22. 22.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) a small bowl (d) yeast
24. 24.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
25. 25.⚖️ 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) False (b) True
26. 26.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) it turned into air (d) the paper ate it
27. 27.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
28. 28.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) white paper (d) a battery cell
30. 30.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) ironing the paper (d) letting the paper dry
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
32. 32.⚖️ 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
33. 33.⚖️ 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 change it (c) we measure it
34. 34.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
35. 35.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) an adult with an iron (d) yeast
37. 37.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
38. 38.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
39. 39.⚖️ 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
40. 40.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False

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