Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 664 · 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.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) turmeric powder (d) an adult with an iron
3. 3.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) cutting the lemon (d) plugging in the iron
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) a balloon
5. 5.⚖️ 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) how dark the writing is (c) the iron setting (d) the kind of juice
6. 6.🍋 Which of these steps is a job for an adult? (a) reading the message (b) cutting the lemon (c) dipping the cotton bud (d) writing the message
7. 7.⚖️ 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
8. 8.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
9. 9.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
10. 10.True or false: plugging in the iron is a job for an adult. (a) True (b) False
11. 11.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) dark brown words (d) almost nothing
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
13. 13.True or false: yeast is needed for the secret lemon message. (a) True (b) False
14. 14.🍋 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
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) the youngest child (d) any child
16. 16.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) letting the paper dry (d) dipping the cotton bud
17. 17.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
18. 18.True or false: white paper is needed for the secret lemon message. (a) True (b) False
19. 19.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
20. 20.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a cotton bud (c) lemon juice (d) white paper
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a cotton bud (d) a battery cell
25. 25.⚖️ 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
26. 26.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
27. 27.⚖️ 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 same cotton bud
28. 28.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) a magnet (d) white paper
30. 30.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) writing the message (c) reading the message (d) dipping the cotton bud
31. 31.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
32. 32.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) letting the paper dry
33. 33.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) ironing the paper
34. 34.True or false: ironing the paper is a job for an adult. (a) True (b) False
35. 35.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) ironing the paper (d) dipping the cotton bud
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
37. 37.⚖️ 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) False (b) True
38. 38.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) letting the paper dry (d) writing the message
39. 39.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
40. 40.⚖️ 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 keep it the same (c) we measure it

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