Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 529 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) yeast (d) lemon juice
2. 2.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) lemon juice (d) an adult with an iron
4. 4.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) dry juice is see-through (d) the paper ate it
5. 5.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) cutting the lemon
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
7. 7.True or false: plugging in the iron is a job a child can do. (a) False (b) True
8. 8.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
9. 9.⚖️ 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) False (b) True
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) white paper (d) a balloon
11. 11.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) reading the message (d) plugging in the iron
12. 12.⚖️ 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
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
14. 14.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
15. 15.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
16. 16.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) writing turns green (d) the paper floats
17. 17.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) white paper (d) yeast
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
19. 19.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a small bowl (c) lemon juice (d) an adult with an iron
21. 21.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a cotton bud (c) an adult with an iron (d) lemon juice
23. 23.⚖️ 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
24. 24.⚖️ 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) the same cotton bud (c) the same paper (d) the kind of juice
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) a mirror (d) yeast
26. 26.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the same cotton bud (d) the same paper
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) a magnet
29. 29.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
30. 30.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
31. 31.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
32. 32.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
33. 33.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
34. 34.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) letting the paper dry (d) plugging in the iron
35. 35.⚖️ 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
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
37. 37.⚖️ 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 measure it (c) we change it
38. 38.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
39. 39.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) writing the message (d) putting the iron away
40. 40.🍋 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

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