Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 265 · 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 — ironing the paper? (a) an adult does it (b) a child can do it
2. 2.True or false: plugging in the iron is a job a child can do. (a) False (b) True
3. 3.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) musical (d) magnetic
4. 4.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
5. 5.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the juice scorches first (d) the iron is brown
6. 6.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
7. 7.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) turmeric powder
9. 9.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) ironing the paper
10. 10.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
11. 11.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
12. 12.⚖️ 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
13. 13.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
14. 14.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the ironing time (c) the kind of juice (d) how dark the writing is
16. 16.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it can burn skin (d) it is sticky
17. 17.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if cooled (d) yes, if shaken
18. 18.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
19. 19.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) ironing the paper (d) putting the iron away
20. 20.True or false: putting the iron away is a job for an adult. (a) False (b) True
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) an adult with an iron (d) a mirror
22. 22.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) reading the message
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 change it (b) we keep it the same (c) we measure it
24. 24.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) letting the paper dry (d) writing the message
25. 25.⚖️ 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 keep it the same (c) we change it
26. 26.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
27. 27.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
28. 28.True or false: reading the message is a job for an adult. (a) False (b) True
29. 29.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
30. 30.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
31. 31.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) dipping the cotton bud (d) plugging in the iron
32. 32.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
33. 33.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
34. 34.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
35. 35.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
36. 36.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) white paper (d) lemon juice
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a battery cell (d) a small bowl
39. 39.⚖️ 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 same paper
40. 40.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) dipping the cotton bud (d) ironing the paper

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