Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 382 · 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: lemon juice is needed for the secret lemon message. (a) False (b) True
2. 2.⚖️ 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 measure it (c) we change it
3. 3.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) musical (d) chemical
4. 4.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
5. 5.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) letting the paper dry (c) reading the message (d) writing the message
6. 6.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) writing the message (d) letting the paper dry
7. 7.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
8. 8.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) a mirror (d) lemon juice
10. 10.True or false: plugging in the iron is a job a child can do. (a) True (b) False
11. 11.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
12. 12.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
13. 13.True or false: writing the message is a job a child can do. (a) False (b) True
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
15. 15.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) blue (d) brown
16. 16.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
17. 17.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) dark brown words (d) a rainbow
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a battery cell (c) an adult with an iron (d) white paper
19. 19.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a balloon (c) lemon juice (d) a small bowl
22. 22.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
23. 23.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
24. 24.True or false: white paper is needed for the secret lemon message. (a) True (b) False
25. 25.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) plugging in the iron (d) putting the iron away
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) a cotton bud (d) lemon juice
27. 27.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is magnetic (d) it is cold
28. 28.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
29. 29.True or false: letting the paper dry is a job a child can do. (a) True (b) False
30. 30.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) putting the iron away (d) reading the message
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) an adult with an iron (d) a battery cell
32. 32.True or false: putting the iron away is a job a child can do. (a) True (b) False
33. 33.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
34. 34.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) reading the message (d) putting the iron away
35. 35.True or false: ironing the paper is a job for an adult. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a small bowl (c) lemon juice (d) an adult with an iron
38. 38.⚖️ 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
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a magnet (d) a cotton bud
40. 40.🍋 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

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