Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 442 · 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 magnet (d) an adult with an iron
2. 2.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
3. 3.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) cutting the lemon
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a cotton bud (d) a battery cell
5. 5.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
6. 6.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
7. 7.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
8. 8.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) ironing the paper
9. 9.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
10. 10.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) putting the iron away (d) writing the message
11. 11.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
12. 12.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
13. 13.⚖️ 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
14. 14.🛟 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
15. 15.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if cooled (d) yes, if shaken
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the kind of juice (d) the same cotton bud
17. 17.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
18. 18.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a magnet (d) white paper
20. 20.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
21. 21.🛟 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
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) yeast (d) an adult with an iron
23. 23.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) dry juice is see-through (d) the ink is magnetic
25. 25.⚖️ 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) False (b) True
26. 26.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) ironing the paper
27. 27.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) a rainbow (d) dark brown words
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) white paper (d) a mirror
29. 29.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) plugging in the iron (d) putting the iron away
30. 30.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
31. 31.🍋 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
32. 32.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) a balloon (d) white paper
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a cotton bud (d) white paper
35. 35.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) writing the message (d) putting the iron away
36. 36.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
37. 37.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) the paper floats (d) writing turns green
38. 38.⚖️ 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
39. 39.True or false: letting the paper dry is a job for an adult. (a) True (b) False
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the ironing time (d) the same paper

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