Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 304 · 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.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the ink is magnetic (d) the paper ate it
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the ironing time
3. 3.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) putting the iron away (d) reading the message
4. 4.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) blue (d) brown
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) a rainbow (d) dark brown words
6. 6.⚖️ 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
7. 7.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
8. 8.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) white paper (c) a battery cell (d) a balloon
11. 11.True or false: cutting the lemon is a job a child can do. (a) False (b) True
12. 12.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
13. 13.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
14. 14.True or false: ironing the paper is a job a child can do. (a) False (b) True
15. 15.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) plugging in the iron (d) letting the paper dry
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) white paper (c) a cotton bud (d) a small bowl
17. 17.🍋 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) cutting the lemon
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a small bowl (d) a battery cell
19. 19.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
20. 20.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a battery cell (d) white paper
23. 23.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
25. 25.⚖️ 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) the same paper (c) the same cotton bud (d) how dark the writing is
26. 26.⚖️ 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
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a mirror (d) white paper
28. 28.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
29. 29.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) reading the message (d) ironing the paper
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) False (b) True
31. 31.⚖️ 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
32. 32.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) cutting the lemon (d) letting the paper dry
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) white paper (d) turmeric powder
35. 35.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
36. 36.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
38. 38.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
39. 39.True or false: putting the iron away is a job a child can do. (a) True (b) False
40. 40.True or false: reading the message is a job for an adult. (a) True (b) False

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