Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 917 · 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 — ironing the paper? (a) a child can do it (b) an adult does it
2. 2.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
3. 3.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) a mirror (d) a cotton bud
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) turmeric powder (d) a small bowl
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a magnet (d) white paper
6. 6.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
7. 7.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
8. 8.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
10. 10.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
11. 11.⚖️ 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
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
13. 13.🔮 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
14. 14.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
15. 15.⚖️ 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 iron setting (c) the same cotton bud (d) the same paper
16. 16.True or false: plugging in the iron is a job a child can do. (a) True (b) False
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a balloon (c) an adult with an iron (d) a cotton bud
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) a small bowl (d) lemon juice
19. 19.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) a rainbow (d) dark brown words
20. 20.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
21. 21.⚖️ 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 ironing time (c) the kind of juice
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) white paper (d) lemon juice
23. 23.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) dry juice is see-through (d) the paper ate it
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) white paper (d) a mirror
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
28. 28.True or false: putting the iron away is a job for an adult. (a) False (b) True
29. 29.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) writing turns green (d) the paper floats
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
31. 31.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
32. 32.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) dipping the cotton bud
33. 33.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) writing the message (d) plugging in the iron
34. 34.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) dipping the cotton bud (d) reading the message
35. 35.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
36. 36.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) white paper (d) yeast
38. 38.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) cutting the lemon (d) writing the message
39. 39.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
40. 40.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) letting the paper dry (d) reading the message

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