Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 514 · 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: a magnet is not needed for the secret lemon message. (a) True (b) False
2. 2.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
3. 3.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) the juice scorches first (d) paper turns lemony
4. 4.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
5. 5.True or false: white paper is needed for the secret lemon message. (a) True (b) False
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a cotton bud (d) turmeric powder
7. 7.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
8. 8.🧺 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) yeast (d) a cotton bud
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a cotton bud (d) a battery cell
10. 10.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) green (d) blue
11. 11.⚖️ 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
12. 12.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
13. 13.True or false: letting the paper dry 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? Which of these is the one thing we change? (a) the same cotton bud (b) how dark the writing is (c) the ironing time (d) the kind of juice
15. 15.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) putting the iron away
16. 16.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) letting the paper dry
17. 17.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
18. 18.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
19. 19.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
20. 20.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
21. 21.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
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 measure it (c) we keep it the same
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) lemon juice (c) a small bowl (d) a cotton bud
24. 24.🍋 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) dipping the cotton bud
25. 25.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
26. 26.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) no, it stays brown (d) yes, in the dark
27. 27.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) letting the paper dry (d) ironing the paper
28. 28.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a mirror (c) a magnet (d) turmeric powder
29. 29.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) turmeric powder (c) an adult with an iron (d) white paper
31. 31.⚖️ 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 measure it (c) we change it
32. 32.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
33. 33.True or false: letting the paper dry is a job for an adult. (a) False (b) True
34. 34.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) dipping the cotton bud
35. 35.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
37. 37.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) writing the message (d) dipping the cotton bud
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a magnet (c) yeast (d) turmeric powder
39. 39.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) yeast (d) a cotton bud

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