Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 226 · 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.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
2. 2.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) magnetic (d) physical
3. 3.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
4. 4.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
5. 5.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
6. 6.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
7. 7.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
8. 8.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
9. 9.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
11. 11.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a battery cell (d) turmeric powder
12. 12.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) white paper (d) a magnet
14. 14.True or false: cutting the lemon is a job a child can do. (a) True (b) False
15. 15.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) the juice scorches first (d) paper turns lemony
16. 16.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) dipping the cotton bud (c) reading the message (d) writing the message
17. 17.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) reading the message (d) putting the iron away
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) a mirror (d) a magnet
19. 19.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) writing the message (d) ironing the paper
20. 20.True or false: plugging in the iron is a job a child can do. (a) False (b) True
21. 21.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
22. 22.🔮 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
23. 23.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) a battery cell
25. 25.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it is magnetic (d) it can burn skin
26. 26.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
27. 27.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) dry juice is see-through (d) the ink is magnetic
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) yeast (c) an adult with an iron (d) a cotton bud
30. 30.🛟 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
31. 31.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) plugging in the iron (d) ironing the paper
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
33. 33.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) putting the iron away (d) writing the message
34. 34.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) cutting the lemon
35. 35.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
36. 36.True or false: white paper is needed for the secret lemon message. (a) True (b) False
37. 37.🧺 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) a cotton bud
38. 38.⚖️ 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
39. 39.⚖️ 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
40. 40.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a cotton bud (c) a mirror (d) yeast

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