Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 263 · 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 — dipping the cotton bud? (a) a child can do it (b) an adult does it
2. 2.🍋 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
3. 3.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) reading the message
4. 4.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) lick your fingers (d) skip washing
5. 5.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
6. 6.True or false: plugging in the iron is a job a child can do. (a) False (b) True
7. 7.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) white paper (c) a balloon (d) yeast
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the same paper (d) the ironing time
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the iron setting (d) the same paper
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) lemon juice (c) yeast (d) a balloon
11. 11.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) lemon juice (d) white paper
13. 13.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) writing the message (c) dipping the cotton bud (d) reading the message
14. 14.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) chemical (d) physical
16. 16.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it can burn skin (d) it is cold
17. 17.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
18. 18.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
19. 19.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) lemon juice (d) a battery cell
21. 21.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
22. 22.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) turmeric powder (c) a small bowl (d) lemon juice
24. 24.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) cutting the lemon
25. 25.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
26. 26.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
27. 27.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
28. 28.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
29. 29.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) cutting the lemon
30. 30.🔮 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
31. 31.True or false: cutting the lemon is a job for an adult. (a) False (b) True
32. 32.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
33. 33.🧺 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) white paper (d) a balloon
34. 34.True or false: putting the iron away is a job a child can do. (a) False (b) True
35. 35.⚖️ 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 change it (c) we keep it the same
36. 36.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) letting the paper dry (d) writing the message
37. 37.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
38. 38.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) heat adds colour (d) the juice scorches first
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
40. 40.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest

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