Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 313 · 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: letting the paper dry is a job a child can do. (a) True (b) False
2. 2.⚖️ 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) True (b) False
3. 3.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
4. 4.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
6. 6.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
7. 7.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) reading the message (d) cutting the lemon
8. 8.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) writing the message (d) plugging in the iron
9. 9.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) a rainbow (d) dark brown words
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) turmeric powder (d) a small bowl
11. 11.⚖️ 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
12. 12.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
13. 13.⚖️ 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 same cotton bud (c) how dark the writing is (d) the ironing time
14. 14.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) putting the iron away (d) dipping the cotton bud
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a cotton bud (d) a mirror
16. 16.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
17. 17.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
18. 18.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
19. 19.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) no, it stays brown (d) yes, if shaken
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the ironing time
22. 22.⚖️ 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
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) a cotton bud (d) a battery cell
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a magnet (d) a cotton bud
25. 25.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same paper (c) how dark the writing is
27. 27.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) heat adds colour (d) paper turns lemony
28. 28.True or false: writing the message is a job for an adult. (a) False (b) True
29. 29.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
30. 30.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) an adult with an iron (c) a balloon (d) a magnet
31. 31.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) an adult with an iron (d) a balloon
33. 33.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
34. 34.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
35. 35.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) cutting the lemon (c) dipping the cotton bud (d) writing the message
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) a small bowl (d) turmeric powder
37. 37.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) writing the message (d) plugging in the iron
38. 38.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) lemon juice (c) a small bowl (d) white paper
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) turmeric powder (d) a cotton bud

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