Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 266 · 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.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
2. 2.🔮 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
3. 3.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
4. 4.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) ironing the paper (d) cutting the lemon
5. 5.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) wash your hands (d) lick your fingers
6. 6.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
7. 7.True or false: yeast is needed for the secret lemon message. (a) False (b) True
8. 8.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
9. 9.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) any child (d) only an adult
10. 10.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
11. 11.⚖️ 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
12. 12.True or false: cutting the lemon is a job for an adult. (a) False (b) True
13. 13.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, in the dark (d) yes, if cooled
14. 14.⚖️ 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
15. 15.🧺 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) a small bowl
16. 16.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it can burn skin (d) it is magnetic
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
18. 18.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) an adult with an iron (d) lemon juice
20. 20.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) a small bowl (d) a balloon
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) lemon juice (d) a balloon
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a mirror (c) a small bowl (d) white paper
24. 24.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) lemon juice (d) yeast
26. 26.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) ironing the paper (d) reading the message
27. 27.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
28. 28.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) chemical (d) physical
29. 29.True or false: ironing the paper is a job for an adult. (a) True (b) False
30. 30.⚖️ 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 iron setting (d) how dark the writing is
31. 31.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
32. 32.True or false: ironing the paper is a job a child can do. (a) False (b) True
33. 33.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
34. 34.⚖️ 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
35. 35.⚖️ 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
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a battery cell (d) a small bowl
37. 37.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) yeast (d) white paper
38. 38.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a small bowl (d) yeast
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False

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