Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 845 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) a battery cell
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
3. 3.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
4. 4.True or false: cutting the lemon is a job a child can do. (a) False (b) True
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a cotton bud (d) an adult with an iron
6. 6.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) a rainbow (d) blue words
7. 7.⚖️ 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
8. 8.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
9. 9.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
10. 10.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
11. 11.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
12. 12.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) putting the iron away (d) dipping the cotton bud
13. 13.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) reading the message
14. 14.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) a mirror (d) a balloon
16. 16.True or false: reading the message is a job for an adult. (a) False (b) True
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) how dark the writing is (c) the iron setting (d) the same paper
18. 18.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
19. 19.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a magnet (d) white paper
22. 22.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
23. 23.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a cotton bud (d) a small bowl
25. 25.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
26. 26.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a balloon (d) a mirror
27. 27.⚖️ 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) how dark the writing is (c) the ironing time
28. 28.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
29. 29.True or false: plugging in the iron is a job a child can do. (a) True (b) False
30. 30.True or false: writing the message is a job a child can do. (a) True (b) False
31. 31.True or false: putting the iron away is a job for an adult. (a) False (b) True
32. 32.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) a small bowl (d) white paper
34. 34.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) dipping the cotton bud
35. 35.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
36. 36.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
37. 37.True or false: reading the message is a job a child can do. (a) False (b) True
38. 38.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
39. 39.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
40. 40.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) paper turns lemony (d) the juice scorches first

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