Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 919 · 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.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) heat adds colour (d) the iron is brown
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) how dark the writing is (c) the kind of juice (d) the same paper
3. 3.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
4. 4.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
5. 5.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) putting the iron away (d) plugging in the iron
6. 6.True or false: plugging in the iron is a job for an adult. (a) False (b) True
7. 7.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) white paper (d) a mirror
9. 9.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) putting the iron away (d) ironing the paper
10. 10.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a mirror (c) turmeric powder (d) a balloon
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a magnet (d) white paper
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) white paper (d) a balloon
13. 13.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
14. 14.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) plugging in the iron (d) cutting the lemon
15. 15.True or false: reading the message is a job a child can do. (a) True (b) False
16. 16.🍋 Which of these steps is a job a child can do? (a) reading the message (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
17. 17.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
18. 18.🛟 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
19. 19.⚖️ 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
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) an adult with an iron (c) a cotton bud (d) lemon juice
21. 21.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
22. 22.⚖️ 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
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
24. 24.⚖️ 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 cotton bud (c) how dark the writing is
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
28. 28.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) ironing the paper (d) dipping the cotton bud
29. 29.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
30. 30.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) lemon juice (d) a balloon
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same cotton bud (c) the kind of juice (d) the same paper
33. 33.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) writing the message (d) plugging in the iron
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
35. 35.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
36. 36.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
37. 37.⚖️ 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
38. 38.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
39. 39.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) an adult with an iron (c) lemon juice (d) white paper

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