Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 857 · 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 steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
2. 2.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) plugging in the iron (c) ironing the paper (d) putting the iron away
3. 3.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) writing the message (d) cutting the lemon
4. 4.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
5. 5.True or false: writing the message is a job for an adult. (a) False (b) True
6. 6.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
7. 7.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
8. 8.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a battery cell (d) turmeric powder
9. 9.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) writing the message (d) dipping the cotton bud
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) a magnet (d) white paper
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) yeast (d) turmeric powder
13. 13.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
14. 14.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) any child (d) the youngest child
15. 15.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
16. 16.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
17. 17.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, if shaken (d) yes, in the dark
18. 18.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
19. 19.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
20. 20.⚖️ 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
21. 21.⚖️ 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 keep it the same (c) we measure it
22. 22.True or false: plugging in the iron is a job a child can do. (a) False (b) True
23. 23.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
24. 24.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
25. 25.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) lemon juice (c) a battery cell (d) turmeric powder
26. 26.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
27. 27.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
28. 28.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
29. 29.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) a rainbow (d) dark brown words
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: turmeric powder is needed for the secret lemon message. (a) True (b) False
32. 32.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
33. 33.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) dipping the cotton bud
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
35. 35.⚖️ 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
36. 36.⚖️ 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 kind of juice (c) the ironing time
37. 37.⚖️ 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 measure it (c) we change it
38. 38.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
40. 40.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) heat adds colour (d) the iron is brown

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