Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 175 · 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.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) a magnet
2. 2.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) writing the message (c) dipping the cotton bud (d) letting the paper dry
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a balloon (d) a cotton bud
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a balloon (c) yeast (d) a mirror
5. 5.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
6. 6.⚖️ 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) the same paper (c) the ironing time (d) the iron setting
7. 7.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
8. 8.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) an adult with an iron (d) turmeric powder
10. 10.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) writing the message
11. 11.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
12. 12.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
13. 13.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
15. 15.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
16. 16.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) writing the message (d) putting the iron away
17. 17.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) a cotton bud (d) a mirror
19. 19.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) reading the message (d) letting the paper dry
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) a cotton bud (d) lemon juice
22. 22.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) green (d) blue
23. 23.⚖️ 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
24. 24.⚖️ 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
25. 25.🧺 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) a cotton bud (d) lemon juice
26. 26.True or false: ironing the paper is a job for an adult. (a) False (b) True
27. 27.True or false: reading the message is a job a child can do. (a) False (b) True
28. 28.True or false: letting the paper dry is a job a child can do. (a) True (b) False
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
30. 30.⚖️ 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) True (b) False
31. 31.True or false: white paper is needed for the secret lemon message. (a) False (b) True
32. 32.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) writing turns green (d) the paper floats
33. 33.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) heat adds colour (d) the iron is brown
34. 34.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
35. 35.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
36. 36.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
37. 37.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
39. 39.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
40. 40.True or false: yeast is not needed for the secret lemon message. (a) False (b) True

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