Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 508 · 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.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
3. 3.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
5. 5.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
6. 6.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a small bowl (c) a magnet (d) a balloon
7. 7.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) plugging in the iron (d) dipping the cotton bud
8. 8.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a magnet (c) a mirror (d) a balloon
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) a cotton bud (d) lemon juice
10. 10.🍋 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) letting the paper dry
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) turmeric powder (c) lemon juice (d) a small bowl
12. 12.🍋 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
13. 13.⚖️ 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 keep it the same (c) we change it
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
15. 15.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
16. 16.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is sticky (d) it is magnetic
17. 17.🛟 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
18. 18.🍋 Which of these steps is a job for an adult? (a) reading the message (b) putting the iron away (c) writing the message (d) letting the paper dry
19. 19.⚖️ 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
20. 20.True or false: letting the paper dry is a job a child can do. (a) False (b) True
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) lemon juice (d) a cotton bud
22. 22.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
23. 23.⚖️ 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
24. 24.🔮 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
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) white paper (d) a mirror
26. 26.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) reading the message (d) putting the iron away
27. 27.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) writing the message (d) cutting the lemon
28. 28.⚖️ 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 measure it (c) we keep it the same
29. 29.True or false: reading the message is a job for an adult. (a) True (b) False
30. 30.🍋 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
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a battery cell (c) lemon juice (d) an adult with an iron
32. 32.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
33. 33.⚖️ 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
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a balloon (c) lemon juice (d) white paper
35. 35.🍋 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) writing the message
36. 36.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
37. 37.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is
39. 39.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) putting the iron away (d) writing the message
40. 40.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it

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