Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 890 · 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.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) reading the message (d) letting the paper dry
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a mirror (d) white paper
3. 3.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
4. 4.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) lemon juice (d) a battery cell
6. 6.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
7. 7.⚖️ 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
8. 8.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) blue (d) green
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) white paper (d) yeast
10. 10.True or false: putting the iron away is a job for an adult. (a) False (b) True
11. 11.⚖️ 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
12. 12.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
13. 13.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
14. 14.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is magnetic (d) it is sticky
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the iron setting (c) the kind of juice (d) the same cotton bud
16. 16.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
17. 17.⚖️ 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
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) almost nothing (d) a rainbow
19. 19.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
20. 20.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) reading the message (d) plugging in the iron
21. 21.True or false: yeast is needed for the secret lemon message. (a) False (b) True
22. 22.🍋 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
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
24. 24.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
25. 25.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) ironing the paper
26. 26.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the ironing time (c) the same cotton bud (d) how dark the writing is
29. 29.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) plugging in the iron
30. 30.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a balloon (c) an adult with an iron (d) white paper
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) a battery cell (d) lemon juice
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) False (b) True
35. 35.True or false: plugging in the iron is a job for an adult. (a) True (b) False
36. 36.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) white paper (d) a small bowl
39. 39.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
40. 40.True or false: plugging in the iron is a job a child can do. (a) True (b) False

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