Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 878 · 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 a child can do. (a) True (b) False
2. 2.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) magnetic (d) musical
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) white paper (d) a magnet
4. 4.⚖️ 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 iron setting (d) the ironing time
5. 5.⚖️ 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 change it (c) we keep it the same
6. 6.🔮 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
7. 7.🛟 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
8. 8.True or false: ironing the paper is a job for an adult. (a) True (b) False
9. 9.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
10. 10.⚖️ 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 keep it the same (c) we measure it
11. 11.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
13. 13.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
14. 14.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) lemon juice (d) a battery cell
16. 16.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
17. 17.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) a magnet (d) a small bowl
19. 19.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
20. 20.🍋 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) writing the message
21. 21.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) reading the message (d) writing the message
22. 22.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) dipping the cotton bud (d) ironing the paper
23. 23.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
24. 24.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) putting the iron away
25. 25.True or false: putting the iron away is a job for an adult. (a) True (b) False
26. 26.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) white paper (c) a balloon (d) yeast
27. 27.True or false: putting the iron away is a job a child can do. (a) True (b) False
28. 28.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) it gets darker (d) writing turns green
29. 29.🔮 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
30. 30.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) plugging in the iron (d) dipping the cotton bud
31. 31.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
32. 32.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) heat adds colour (d) paper turns lemony
33. 33.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
34. 34.True or false: letting the paper dry is a job for an adult. (a) False (b) True
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a small bowl (d) a mirror
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
37. 37.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) an adult with an iron (d) lemon juice
39. 39.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
40. 40.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) letting the paper dry (c) dipping the cotton bud (d) reading the message

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