Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 154 · 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 is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a cotton bud (d) a mirror
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
3. 3.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
4. 4.True or false: reading the message is a job for an adult. (a) True (b) False
5. 5.⚖️ 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
6. 6.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
7. 7.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
9. 9.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
10. 10.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
11. 11.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) wash your hands (d) skip washing
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) a cotton bud (d) white paper
13. 13.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) writing the message
14. 14.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) a mirror (d) turmeric powder
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) white paper (d) an adult with an iron
16. 16.⚖️ 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) the same paper (c) how dark the writing is
17. 17.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
18. 18.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) the paper ate it (d) dry juice is see-through
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) a magnet (d) white paper
20. 20.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) dipping the cotton bud (d) letting the paper dry
21. 21.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) heat adds colour (d) paper turns lemony
22. 22.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
23. 23.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) a balloon (d) a mirror
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.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
26. 26.🧺 Do we need a mirror 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 kind of juice is the one thing we change. (a) True (b) False
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is (d) the same paper
29. 29.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) an adult with an iron (d) white paper
31. 31.⚖️ 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
32. 32.⚖️ 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 ironing time
33. 33.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
34. 34.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
35. 35.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) cutting the lemon (d) letting the paper dry
36. 36.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) letting the paper dry (d) plugging in the iron
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) turmeric powder (d) white paper
38. 38.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
39. 39.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
40. 40.🔮 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

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