Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 964 · 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 not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a cotton bud (d) a magnet
2. 2.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) the ink is magnetic (d) it turned into air
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a cotton bud (d) a magnet
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) lemon juice (d) a small bowl
5. 5.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
6. 6.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it can burn skin (d) it is magnetic
7. 7.⚖️ 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 change it (c) we keep it the same
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) white paper (c) a cotton bud (d) lemon juice
10. 10.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
11. 11.🍋 Which of these steps is a job for an adult? (a) writing the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
12. 12.True or false: ironing the paper is a job for an adult. (a) False (b) True
13. 13.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
14. 14.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
15. 15.⚖️ 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
16. 16.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) musical (d) magnetic
17. 17.⚖️ 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) True (b) False
18. 18.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
19. 19.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
20. 20.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
21. 21.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
22. 22.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) heat adds colour (d) the iron is brown
23. 23.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) cutting the lemon
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) white paper (d) yeast
25. 25.True or false: putting the iron away is a job a child can do. (a) True (b) False
26. 26.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
27. 27.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
28. 28.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a battery cell (c) yeast (d) a balloon
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
30. 30.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
31. 31.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does 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 same cotton bud
33. 33.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) putting the iron away
34. 34.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) turmeric powder (d) a small bowl
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the ironing time (d) the iron setting
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) yeast (d) an adult with an iron
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) turmeric powder (d) an adult with an iron
38. 38.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
39. 39.⚖️ 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
40. 40.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True

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