Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 977 · 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 yeast for the secret lemon message? (a) needed (b) not needed
2. 2.⚖️ 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 keep it the same (c) we measure it
3. 3.True or false: cutting the lemon is a job a child can do. (a) True (b) False
4. 4.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) it gets darker (d) writing turns green
5. 5.True or false: ironing the paper is a job a child can do. (a) False (b) True
6. 6.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
7. 7.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
8. 8.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a balloon (d) a small bowl
10. 10.⚖️ 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 ironing time (c) the same paper (d) the iron setting
11. 11.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) cutting the lemon (d) putting the iron away
12. 12.⚖️ 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 iron setting (c) how dark the writing is
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) an adult with an iron (d) a small bowl
14. 14.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
15. 15.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
16. 16.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
17. 17.⚖️ 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
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
19. 19.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
20. 20.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) white paper (c) a cotton bud (d) lemon juice
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a small bowl (d) white paper
23. 23.True or false: putting the iron away is a job for an adult. (a) False (b) True
24. 24.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
25. 25.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
26. 26.🧺 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
27. 27.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) rub your eyes (d) wash your hands
28. 28.🧺 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) turmeric powder
29. 29.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) reading the message (d) dipping the cotton bud
30. 30.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
31. 31.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
32. 32.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
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 kind of juice (b) the ironing time (c) how dark the writing is (d) the same cotton bud
34. 34.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) plugging in the iron (d) writing the message
35. 35.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) lemon juice (c) an adult with an iron (d) a small bowl
37. 37.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
38. 38.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) yeast (d) a cotton bud

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