Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 323 · 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.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is magnetic (d) it is cold
2. 2.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
3. 3.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) putting the iron away (d) plugging in the iron
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) white paper (c) a cotton bud (d) lemon juice
5. 5.🍋 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
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) white paper (d) an adult with an iron
7. 7.⚖️ 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 change it (c) we measure it
8. 8.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) reading the message (d) ironing the paper
9. 9.⚖️ 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
10. 10.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a balloon (d) lemon juice
11. 11.🍋 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
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) white paper (c) a cotton bud (d) an adult with an iron
13. 13.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) dipping the cotton bud (d) writing the message
14. 14.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
15. 15.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) plugging in the iron (c) ironing the paper (d) putting the iron away
16. 16.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
17. 17.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) letting the paper dry (c) plugging in the iron (d) ironing the paper
18. 18.True or false: reading the message is a job for an adult. (a) False (b) True
19. 19.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) a balloon (d) white paper
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
22. 22.⚖️ 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
23. 23.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) the paper floats (d) writing stays faint
24. 24.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
25. 25.⚖️ 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 same paper (c) the ironing time (d) the kind of juice
26. 26.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) an adult with an iron (d) a cotton bud
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the ironing time (c) the same cotton bud (d) how dark the writing is
29. 29.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
31. 31.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
32. 32.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) an adult with an iron (c) yeast (d) a mirror
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) an adult with an iron (d) white paper
34. 34.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) plugging in the iron (d) ironing the paper
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) white paper (d) turmeric powder
36. 36.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
37. 37.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
38. 38.⚖️ 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 same cotton bud (c) the kind of juice
39. 39.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) writing the message
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a cotton bud (c) white paper (d) lemon juice

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