Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 330 · 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: white paper is needed for the secret lemon message. (a) False (b) True
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) turmeric powder (c) a cotton bud (d) lemon juice
3. 3.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) putting the iron away (d) cutting the lemon
4. 4.True or false: ironing the paper is a job a child can do. (a) True (b) False
5. 5.True or false: reading the message is a job for an adult. (a) True (b) False
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud (d) the ironing time
7. 7.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) an adult with an iron (d) a mirror
9. 9.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
10. 10.⚖️ 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
11. 11.🛟 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
12. 12.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
13. 13.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
14. 14.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) the ink is magnetic (d) it turned into air
15. 15.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) the paper floats (d) writing turns green
16. 16.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) putting the iron away
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) an adult with an iron (c) lemon juice (d) white paper
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) a magnet (d) turmeric powder
19. 19.⚖️ 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
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) an adult with an iron (d) a mirror
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a small bowl (c) a cotton bud (d) white paper
22. 22.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a balloon (d) a small bowl
24. 24.⚖️ 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
25. 25.True or false: cutting the lemon is a job for an adult. (a) True (b) False
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) lemon juice (c) a cotton bud (d) white paper
27. 27.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) turmeric powder (d) a mirror
29. 29.True or false: letting the paper dry is a job a child can do. (a) False (b) True
30. 30.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
31. 31.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
32. 32.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
33. 33.🍋 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
34. 34.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
35. 35.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, in the dark (d) yes, if cooled
36. 36.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) putting the iron away
37. 37.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) dipping the cotton bud (d) writing the message
38. 38.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
39. 39.True or false: writing the message is a job a child can do. (a) True (b) False
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is

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