Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 748 · 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.True or false: letting the paper dry is a job for an adult. (a) False (b) True
2. 2.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) cutting the lemon (d) plugging in the iron
3. 3.True or false: white paper is needed for the secret lemon message. (a) True (b) False
4. 4.🍋 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
5. 5.🔮 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
6. 6.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) writing the message
7. 7.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) writing the message (c) cutting the lemon (d) putting the iron away
8. 8.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) putting the iron away (c) writing the message (d) reading the message
9. 9.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
10. 10.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
11. 11.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) ironing the paper (d) putting the iron away
12. 12.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
13. 13.⚖️ 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 paper (d) how dark the writing is
14. 14.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) a magnet (d) a balloon
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
16. 16.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
17. 17.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
18. 18.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) writing turns green (d) the paper floats
19. 19.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a battery cell (c) an adult with an iron (d) a small bowl
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a mirror (c) an adult with an iron (d) lemon juice
22. 22.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
23. 23.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) dipping the cotton bud
24. 24.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) reading the message (d) writing the message
25. 25.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
27. 27.🛟 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
28. 28.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
29. 29.True or false: ironing the paper is a job for an adult. (a) False (b) True
30. 30.🧺 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
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a mirror (c) an adult with an iron (d) white paper
32. 32.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
33. 33.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
35. 35.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
36. 36.⚖️ 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 kind of juice (c) the iron setting
37. 37.⚖️ 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
38. 38.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) letting the paper dry (d) cutting the lemon
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
40. 40.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) putting the iron away (d) reading the message

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