Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 528 · 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.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) lemon juice (d) a cotton bud
3. 3.⚖️ 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
4. 4.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
5. 5.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
6. 6.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) dipping the cotton bud (c) letting the paper dry (d) reading the message
7. 7.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it can burn skin (d) it is cold
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) white paper (c) a balloon (d) a battery cell
9. 9.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
10. 10.True or false: ironing the paper is a job for an adult. (a) True (b) False
11. 11.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) writing the message
12. 12.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) ironing the paper
13. 13.True or false: putting the iron away is a job for an adult. (a) False (b) True
14. 14.True or false: writing the message is a job for an adult. (a) True (b) False
15. 15.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) dark brown words (d) blue words
16. 16.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) writing turns green (d) it gets darker
17. 17.⚖️ 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 same paper (c) the kind of juice (d) how dark the writing is
18. 18.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) yeast (c) lemon juice (d) white paper
20. 20.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) a mirror (d) a battery cell
22. 22.🧺 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
23. 23.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) how dark the writing is (c) the kind of juice (d) the ironing time
25. 25.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) skip washing (d) rub your eyes
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
27. 27.True or false: plugging in the iron is a job for an adult. (a) True (b) False
28. 28.🔍 Which is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) reading the message (d) writing the message
29. 29.True or false: ironing the paper is a job a child can do. (a) True (b) False
30. 30.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) the juice scorches first (d) paper turns lemony
31. 31.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
32. 32.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) putting the iron away (d) plugging in the iron
33. 33.🧺 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 balloon (d) lemon juice
34. 34.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
36. 36.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
37. 37.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
38. 38.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) dry juice is see-through (d) it turned into air
39. 39.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) letting the paper dry (d) putting the iron away
40. 40.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed

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