Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 405 · 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) ironing the paper (b) writing the message (c) cutting the lemon (d) plugging in the iron
2. 2.True or false: yeast is needed for the secret lemon message. (a) False (b) True
3. 3.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) ironing the paper
4. 4.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
5. 5.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
6. 6.True or false: ironing the paper is a job a child can do. (a) True (b) False
7. 7.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) a cotton bud (d) an adult with an iron
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a small bowl (c) lemon juice (d) white paper
10. 10.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) turmeric powder (d) a cotton bud
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a battery cell (d) a small bowl
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) white paper (d) a battery cell
14. 14.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
15. 15.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the ironing time (c) the kind of juice (d) how dark the writing is
17. 17.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) yeast (d) a cotton bud
19. 19.⚖️ 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
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
21. 21.⚖️ 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 measure it (c) we keep it the same
22. 22.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
23. 23.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) magnetic (d) musical
24. 24.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) writing the message
25. 25.True or false: cutting the lemon is a job a child can do. (a) False (b) True
26. 26.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
27. 27.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
28. 28.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) a cotton bud (d) a magnet
30. 30.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
31. 31.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) letting the paper dry (d) cutting the lemon
32. 32.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
33. 33.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) ironing the paper
34. 34.⚖️ 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
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a mirror (d) a balloon
36. 36.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if cooled (d) yes, if shaken
37. 37.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) plugging in the iron
38. 38.True or false: writing the message is a job a child can do. (a) True (b) False
39. 39.True or false: plugging in the iron is a job for an adult. (a) False (b) True
40. 40.True or false: white paper is not needed for the secret lemon message. (a) True (b) False

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