Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 868 · 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.⚖️ 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) how dark the writing is (c) the kind of juice (d) the same cotton bud
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a magnet (d) white paper
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a cotton bud (d) yeast
4. 4.⚖️ 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
5. 5.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
6. 6.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) lemon juice (d) a battery cell
7. 7.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
8. 8.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
9. 9.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
11. 11.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) ironing the paper (d) writing the message
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the ironing time (c) the kind of juice
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
14. 14.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
15. 15.True or false: letting the paper dry is a job for an adult. (a) True (b) False
16. 16.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
17. 17.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
18. 18.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) putting the iron away
19. 19.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the iron is brown (d) the juice scorches first
20. 20.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a balloon (d) white paper
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
22. 22.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) a small bowl (d) a mirror
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) white paper (c) an adult with an iron (d) a cotton bud
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the same cotton bud (c) the kind of juice
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) white paper (d) lemon juice
26. 26.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) letting the paper dry
27. 27.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
28. 28.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
29. 29.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) plugging in the iron (d) ironing the paper
30. 30.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
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.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is cold (d) it is sticky
33. 33.⚖️ 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
34. 34.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
35. 35.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) writing the message
36. 36.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) dipping the cotton bud (d) letting the paper dry
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) white paper (d) a mirror
38. 38.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
39. 39.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a balloon (c) lemon juice (d) a cotton bud

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