Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 612 · 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.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) letting the paper dry (d) writing the message
2. 2.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) putting the iron away (d) cutting the lemon
3. 3.True or false: reading the message is a job a child can do. (a) True (b) False
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the iron setting (c) the kind of juice (d) the same paper
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a cotton bud (c) turmeric powder (d) yeast
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) a mirror (d) lemon juice
7. 7.True or false: letting the paper dry is a job for an adult. (a) False (b) True
8. 8.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
9. 9.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
10. 10.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
11. 11.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) it turned into air (d) the paper ate it
12. 12.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the kind of juice (c) the same cotton bud (d) how dark the writing is
14. 14.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) writing the message (d) plugging in the iron
15. 15.⚖️ 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
16. 16.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
17. 17.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
18. 18.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) turmeric powder (c) yeast (d) a balloon
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) a mirror (d) an adult with an iron
20. 20.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
21. 21.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) physical (d) musical
22. 22.True or false: writing the message is a job for an adult. (a) True (b) False
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) wash your hands (d) skip washing
24. 24.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) plugging in the iron (d) putting the iron away
25. 25.True or false: yeast is needed for the secret lemon message. (a) True (b) False
26. 26.True or false: ironing the paper is a job for an adult. (a) True (b) False
27. 27.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
28. 28.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
29. 29.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) letting the paper dry (d) cutting the lemon
30. 30.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) letting the paper dry
31. 31.True or false: white paper is needed for the secret lemon message. (a) False (b) True
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a balloon (c) a small bowl (d) a cotton bud
33. 33.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
34. 34.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) a rainbow (d) dark brown words
35. 35.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) writing the message (d) reading the message
36. 36.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
37. 37.True or false: cutting the lemon is a job for an adult. (a) False (b) True
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) lemon juice (d) a balloon
39. 39.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) letting the paper dry (d) ironing the paper
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) turmeric powder (d) an adult with an iron

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