Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 908 · 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.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) an adult with an iron (d) lemon juice
4. 4.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) plugging in the iron (d) putting the iron away
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a balloon (c) an adult with an iron (d) white paper
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) yeast (c) white paper (d) a small bowl
7. 7.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) yeast (c) lemon juice (d) a small bowl
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) lemon juice (d) a balloon
10. 10.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a small bowl (d) a magnet
11. 11.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
12. 12.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
14. 14.True or false: white paper is needed for the secret lemon message. (a) False (b) True
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) turmeric powder
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 same paper (b) the ironing time (c) the kind of juice (d) the iron setting
17. 17.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
18. 18.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
19. 19.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) letting the paper dry (d) putting the iron away
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
21. 21.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
22. 22.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
23. 23.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
24. 24.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) putting the iron away (d) dipping the cotton bud
25. 25.True or false: ironing the paper is a job for an adult. (a) True (b) False
26. 26.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) almost nothing (d) blue words
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the kind of juice (c) the ironing time (d) the iron setting
28. 28.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
29. 29.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
30. 30.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) plugging in the iron (c) reading the message (d) writing the message
31. 31.🧺 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) a magnet (d) lemon juice
32. 32.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
34. 34.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) a balloon (d) yeast
35. 35.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it can burn skin (d) it is magnetic
36. 36.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
37. 37.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
38. 38.⚖️ 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
39. 39.⚖️ 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
40. 40.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True

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