Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 896 · 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.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a battery cell (d) lemon juice
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is (d) the same paper
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) lemon juice (d) an adult with an iron
5. 5.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) letting the paper dry (d) writing the message
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
7. 7.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) plugging in the iron (d) reading the message
8. 8.True or false: ironing the paper is a job for an adult. (a) False (b) True
9. 9.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
10. 10.True or false: white paper is needed for the secret lemon message. (a) False (b) True
11. 11.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
12. 12.True or false: yeast is needed for the secret lemon message. (a) True (b) False
13. 13.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
14. 14.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a battery cell (d) a cotton bud
16. 16.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
17. 17.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) turmeric powder (d) a cotton bud
19. 19.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) reading the message (d) plugging in the iron
20. 20.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) a magnet
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a cotton bud (d) yeast
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
24. 24.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
25. 25.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
28. 28.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) an adult with an iron (d) a battery cell
30. 30.⚖️ 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 ironing time (c) how dark the writing is (d) the same cotton bud
31. 31.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
32. 32.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
33. 33.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) putting the iron away (d) ironing the paper
34. 34.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
35. 35.🍋 Which of these steps is a job a child can do? (a) reading the message (b) putting the iron away (c) cutting the lemon (d) ironing the paper
36. 36.⚖️ 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
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) yeast (c) lemon juice (d) a cotton bud
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
39. 39.⚖️ 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
40. 40.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) writing the message (d) putting the iron away

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