Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 82 · 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) lemon juice (c) a mirror (d) a cotton bud
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) a battery cell
3. 3.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) turmeric powder (d) an adult with an iron
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) an adult with an iron (d) yeast
6. 6.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) cutting the lemon (d) plugging in the iron
7. 7.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
8. 8.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
10. 10.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the paper ate it (d) the ink is magnetic
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a magnet (d) white paper
12. 12.⚖️ 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
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) whoever is fastest (d) the youngest child
14. 14.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) plugging in the iron
15. 15.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
16. 16.True or false: putting the iron away is a job a child can do. (a) True (b) False
17. 17.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) white paper (c) turmeric powder (d) a magnet
18. 18.🔮 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
19. 19.⚖️ 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
20. 20.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
21. 21.⚖️ 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 kind of juice (c) the iron setting (d) the same paper
22. 22.🍋 Which of these steps is a job for an adult? (a) writing the message (b) ironing the paper (c) dipping the cotton bud (d) reading the message
23. 23.True or false: cutting the lemon is a job a child can do. (a) False (b) True
24. 24.⚖️ 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 measure it (c) we keep it the same
25. 25.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
26. 26.⚖️ 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 measure it (c) we keep it the same
27. 27.🍋 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
28. 28.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
29. 29.🔍 Which is the odd one out? (a) letting the paper dry (b) putting the iron away (c) reading the message (d) writing the message
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) a small bowl (d) an adult with an iron
31. 31.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) dipping the cotton bud
32. 32.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
33. 33.⚖️ 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 ironing time (c) the kind of juice (d) how dark the writing is
34. 34.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
35. 35.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
36. 36.True or false: writing the message is a job for an adult. (a) True (b) False
37. 37.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) putting the iron away (d) cutting the lemon
38. 38.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) lick your fingers (d) skip washing
39. 39.⚖️ 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
40. 40.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it can burn skin (d) it is cold

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