Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 478 · 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 of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) reading the message
2. 2.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
3. 3.⚖️ 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 change it (c) we keep it the same
4. 4.True or false: plugging in the iron is a job for an adult. (a) False (b) True
5. 5.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
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) the same paper (c) how dark the writing is (d) the same cotton bud
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) a small bowl (d) a cotton bud
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) yeast (d) a balloon
9. 9.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a cotton bud (d) a magnet
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
11. 11.True or false: reading the message is a job a child can do. (a) True (b) False
12. 12.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
13. 13.⚖️ 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
14. 14.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
15. 15.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
16. 16.⚖️ 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
17. 17.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
18. 18.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
19. 19.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
20. 20.True or false: ironing the paper is a job for an adult. (a) True (b) False
21. 21.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
22. 22.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
23. 23.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
24. 24.🔍 Which is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) ironing the paper (d) putting the iron away
25. 25.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
26. 26.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) blue words (d) dark brown words
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) white paper (d) a battery cell
28. 28.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
30. 30.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) brown (d) blue
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a cotton bud (d) white paper
32. 32.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is sticky (d) it is magnetic
33. 33.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) ironing the paper (d) putting the iron away
34. 34.True or false: writing the message is a job for an adult. (a) True (b) False
35. 35.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) white paper (d) a small bowl
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.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
39. 39.⚖️ 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 change it (c) we measure it
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a cotton bud (d) a mirror

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