Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 80 · 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) an adult does it (b) a child can do it
2. 2.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
3. 3.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
4. 4.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
5. 5.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) white paper (d) a cotton bud
8. 8.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the same paper (c) how dark the writing is (d) the same cotton bud
10. 10.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is cold (d) it is sticky
11. 11.True or false: yeast is needed for the secret lemon message. (a) True (b) False
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the same cotton bud (c) the kind of juice (d) the iron setting
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a cotton bud (d) a magnet
14. 14.⚖️ 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
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a cotton bud (c) an adult with an iron (d) lemon juice
16. 16.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, in the dark (d) yes, if shaken
17. 17.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) putting the iron away (c) reading the message (d) dipping the cotton bud
18. 18.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) a magnet (d) a cotton bud
19. 19.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
20. 20.⚖️ 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 measure it (c) we keep it the same
21. 21.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
22. 22.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) dipping the cotton bud (c) writing the message (d) reading the message
23. 23.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) almost nothing (d) blue words
24. 24.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) putting the iron away (d) reading the message
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a battery cell (c) a small bowl (d) lemon juice
26. 26.🛟 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
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) a small bowl (d) turmeric powder
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a balloon (d) a small bowl
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) lemon juice (d) a mirror
30. 30.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
31. 31.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
32. 32.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
33. 33.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) white paper (d) yeast
34. 34.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
35. 35.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
37. 37.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) cutting the lemon (d) putting the iron away
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
39. 39.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
40. 40.⚖️ 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

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