Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 386 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
3. 3.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
4. 4.🧺 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) white paper (d) a mirror
5. 5.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) writing the message (c) putting the iron away (d) plugging in the iron
6. 6.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
7. 7.True or false: reading the message is a job a child can do. (a) True (b) False
8. 8.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) letting the paper dry
9. 9.True or false: letting the paper dry is a job a child can do. (a) False (b) True
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 battery cell (d) lemon juice
11. 11.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
12. 12.⚖️ 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
13. 13.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
14. 14.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) reading the message
15. 15.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
16. 16.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) writing the message (d) putting the iron away
17. 17.⚖️ 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 change it (c) we measure it
18. 18.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) cutting the lemon (d) reading the message
19. 19.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
20. 20.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
21. 21.⚖️ 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
22. 22.🧺 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) a balloon (d) lemon juice
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
24. 24.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
26. 26.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
27. 27.⚖️ 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
28. 28.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) the iron is brown (d) heat adds colour
29. 29.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) plugging in the iron
30. 30.⚖️ 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
31. 31.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
32. 32.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
33. 33.⚖️ 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) False (b) True
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
35. 35.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) writing the message (d) ironing the paper
36. 36.True or false: cutting the lemon is a job a child can do. (a) False (b) True
37. 37.True or false: plugging in the iron is a job a child can do. (a) True (b) False
38. 38.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
39. 39.🧺 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) a small bowl (d) yeast
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) yeast (d) white paper

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