Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 891 · 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? True or false: how dark the writing is is the one thing we change. (a) False (b) True
2. 2.🧺 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) lemon juice (d) a small bowl
3. 3.True or false: letting the paper dry is a job for an adult. (a) False (b) True
4. 4.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
6. 6.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) reading the message (d) putting the iron away
7. 7.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
8. 8.True or false: letting the paper dry is a job a child can do. (a) False (b) True
9. 9.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
10. 10.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
11. 11.True or false: cutting the lemon is a job for an adult. (a) False (b) True
12. 12.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
13. 13.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
14. 14.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) green (d) blue
15. 15.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) plugging in the iron (d) reading the message
16. 16.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) a small bowl (d) an adult with an iron
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) a rainbow (d) almost nothing
19. 19.True or false: reading the message is a job for an adult. (a) False (b) True
20. 20.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
21. 21.True or false: plugging in the iron is a job for an adult. (a) False (b) True
22. 22.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a balloon (c) an adult with an iron (d) a small bowl
24. 24.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
25. 25.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) ironing the paper (d) dipping the cotton bud
26. 26.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) an adult with an iron (d) lemon juice
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a cotton bud (c) white paper (d) lemon juice
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a battery cell (d) white paper
31. 31.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) dipping the cotton bud (d) letting the paper dry
32. 32.⚖️ 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
33. 33.True or false: putting the iron away is a job a child can do. (a) False (b) True
34. 34.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
35. 35.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) the iron is brown (d) heat adds colour
36. 36.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the iron setting (c) the same paper (d) how dark the writing is
39. 39.⚖️ 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 change it (c) we keep it the same
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) turmeric powder

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