Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 512 · 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 must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it can burn skin (d) it is sticky
2. 2.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a battery cell (c) a mirror (d) turmeric powder
3. 3.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
4. 4.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a mirror (c) lemon juice (d) a cotton bud
6. 6.True or false: reading the message is a job for an adult. (a) True (b) False
7. 7.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the iron is brown (d) the juice scorches first
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
9. 9.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
10. 10.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
11. 11.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) skip washing (d) rub your eyes
12. 12.True or false: writing the message is a job a child can do. (a) True (b) False
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the ironing time (d) the same paper
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a small bowl (c) white paper (d) an adult with an iron
15. 15.⚖️ 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 change it (c) we keep it the same
16. 16.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
17. 17.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) yeast (d) lemon juice
19. 19.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
20. 20.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) any child (d) the youngest child
21. 21.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) dry juice is see-through (d) the paper ate it
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) an adult with an iron (d) lemon juice
23. 23.🍋 Which of these steps is a job for an adult? (a) writing the message (b) ironing the paper (c) reading the message (d) letting the paper dry
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
25. 25.True or false: yeast is needed for the secret lemon message. (a) True (b) False
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a small bowl (d) a balloon
27. 27.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
28. 28.⚖️ 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 measure it (c) we keep it the same
29. 29.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, in the dark (d) yes, if cooled
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) yeast (d) a small bowl
31. 31.⚖️ 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
32. 32.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
33. 33.True or false: plugging in the iron is a job for an adult. (a) True (b) False
34. 34.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
35. 35.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
36. 36.True or false: cutting the lemon is a job for an adult. (a) False (b) True
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
38. 38.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) a cotton bud (d) white paper
40. 40.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed

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