Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 7 · 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) letting the paper dry (b) dipping the cotton bud (c) cutting the lemon (d) writing the message
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) turmeric powder (d) lemon juice
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a magnet (d) a cotton bud
4. 4.True or false: cutting the lemon is a job for an adult. (a) False (b) True
5. 5.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) rub your eyes (d) lick your fingers
6. 6.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud
8. 8.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) letting the paper dry (d) plugging in the iron
9. 9.True or false: ironing the paper is a job a child can do. (a) True (b) False
10. 10.True or false: cutting the lemon is a job a child can do. (a) False (b) True
11. 11.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
12. 12.⚖️ 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
13. 13.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
14. 14.True or false: yeast is needed for the secret lemon message. (a) False (b) True
15. 15.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
16. 16.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
17. 17.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) blue words (d) a rainbow
18. 18.True or false: writing the message is a job for an adult. (a) False (b) True
19. 19.⚖️ 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
20. 20.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) lemon juice (c) a battery cell (d) a mirror
21. 21.⚖️ 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
22. 22.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) dipping the cotton bud (d) putting the iron away
23. 23.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
24. 24.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
25. 25.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) dipping the cotton bud (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? True or false: the ironing time is kept the same. (a) False (b) True
28. 28.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
29. 29.⚖️ 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
30. 30.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) plugging in the iron (d) dipping the cotton bud
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) how dark the writing is (c) the same cotton bud (d) the kind of juice
32. 32.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
33. 33.🛟 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
34. 34.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) letting the paper dry (d) putting the iron away
35. 35.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
36. 36.🛟 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
37. 37.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) a cotton bud (d) a battery cell
39. 39.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
40. 40.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it

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