Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 146 · 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.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
2. 2.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a balloon (c) a small bowl (d) a cotton bud
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a magnet (d) a small bowl
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
6. 6.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
7. 7.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) heat adds colour (d) the juice scorches first
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) lemon juice (d) a cotton bud
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) yeast (d) a small bowl
10. 10.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a battery cell (c) an adult with an iron (d) a magnet
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the ironing time (d) the same paper
12. 12.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
13. 13.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
15. 15.⚖️ 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
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) how dark the writing is (c) the kind of juice (d) the ironing time
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) lemon juice (d) a cotton bud
18. 18.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) only an adult (d) any child
19. 19.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
20. 20.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) cutting the lemon (d) reading the message
21. 21.True or false: ironing the paper is a job for an adult. (a) False (b) True
22. 22.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
24. 24.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
25. 25.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
26. 26.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) writing the message
27. 27.⚖️ 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 measure it (c) we keep it the same
28. 28.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
29. 29.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
31. 31.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) rub your eyes (d) wash your hands
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) a cotton bud (d) an adult with an iron
33. 33.True or false: putting the iron away is a job a child can do. (a) False (b) True
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) white paper (c) an adult with an iron (d) lemon juice
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) an adult with an iron (d) a battery cell
36. 36.True or false: white paper is needed for the secret lemon message. (a) True (b) False
37. 37.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
38. 38.True or false: plugging in the iron is a job a child can do. (a) True (b) False
39. 39.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) blue (d) green
40. 40.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True

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