Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 764 · 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.True or false: plugging in the iron is a job for an adult. (a) False (b) True
2. 2.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) cutting the lemon (d) plugging in the iron
3. 3.🛟 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
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
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 change it (b) we keep it the same (c) we measure it
6. 6.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a battery cell (c) lemon juice (d) a cotton bud
8. 8.⚖️ 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 measure it (c) we keep it the same
9. 9.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) yeast (d) an adult with an iron
11. 11.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
12. 12.⚖️ 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
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) lemon juice (c) a balloon (d) yeast
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
16. 16.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) reading the message (c) putting the iron away (d) plugging in the iron
17. 17.🛟 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
18. 18.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) turmeric powder (d) white paper
21. 21.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) dark brown words (d) a rainbow
22. 22.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
23. 23.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
24. 24.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
25. 25.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) plugging in the iron (d) reading the message
26. 26.True or false: reading the message is a job for an adult. (a) True (b) False
27. 27.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
29. 29.True or false: ironing the paper is a job for an adult. (a) True (b) False
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the ironing time (c) the kind of juice (d) the iron setting
31. 31.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
32. 32.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
33. 33.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) green (d) blue
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) yeast (c) a cotton bud (d) white paper
35. 35.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
36. 36.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
37. 37.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
38. 38.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
39. 39.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) lemon juice (d) a balloon

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