Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 972 · 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.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
2. 2.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) a magnet (d) a cotton bud
3. 3.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
5. 5.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we keep it the same (c) we change it
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
8. 8.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
9. 9.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
11. 11.True or false: reading the message is a job for an adult. (a) False (b) True
12. 12.⚖️ 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 same cotton bud (c) how dark the writing is (d) the iron setting
13. 13.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a battery cell (c) a small bowl (d) lemon juice
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) white paper (d) a magnet
16. 16.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
17. 17.⚖️ 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
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
19. 19.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
20. 20.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
21. 21.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
22. 22.⚖️ 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 ironing time (c) how dark the writing is
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) yeast (d) a small bowl
24. 24.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
25. 25.True or false: writing the message is a job for an adult. (a) True (b) False
26. 26.⚖️ 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
27. 27.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
28. 28.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) plugging in the iron (d) reading the message
29. 29.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
30. 30.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
31. 31.True or false: writing the message is a job a child can do. (a) False (b) True
32. 32.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
33. 33.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) letting the paper dry (d) cutting the lemon
34. 34.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) dipping the cotton bud
35. 35.True or false: cutting the lemon is a job for an adult. (a) False (b) True
36. 36.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
37. 37.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) cutting the lemon
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) an adult with an iron (d) a battery cell
39. 39.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
40. 40.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) reading the message (c) writing the message (d) letting the paper dry

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