Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 437 · 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.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
2. 2.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
3. 3.⚖️ 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
4. 4.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) dipping the cotton bud (d) putting the iron away
5. 5.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) reading the message
6. 6.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
7. 7.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) reading the message (d) plugging in the iron
8. 8.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) cutting the lemon (c) letting the paper dry (d) writing the message
9. 9.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
10. 10.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
11. 11.⚖️ 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) False (b) True
12. 12.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the ironing time (c) how dark the writing is (d) the kind of juice
14. 14.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, in the dark (d) yes, if shaken
15. 15.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) a cotton bud (d) an adult with an iron
17. 17.True or false: reading the message is a job a child can do. (a) True (b) False
18. 18.⚖️ 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
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) lemon juice (c) a small bowl (d) an adult with an iron
21. 21.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) letting the paper dry (d) reading the message
22. 22.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
23. 23.True or false: ironing the paper is a job a child can do. (a) True (b) False
24. 24.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
25. 25.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
26. 26.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) dipping the cotton bud
27. 27.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is magnetic (d) it is sticky
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 measure it (c) we keep it the same
29. 29.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
30. 30.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) dipping the cotton bud
31. 31.🧺 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) an adult with an iron
32. 32.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
33. 33.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a balloon (d) white paper
35. 35.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the kind of juice (c) the same paper (d) the same cotton bud
37. 37.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
38. 38.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
39. 39.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is

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