Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 991 · 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.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) dark brown words (d) a rainbow
2. 2.⚖️ 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 change it (c) we keep it the same
3. 3.True or false: ironing the paper is a job for an adult. (a) True (b) False
4. 4.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a mirror (c) turmeric powder (d) a magnet
5. 5.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
6. 6.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) putting the iron away (d) cutting the lemon
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) a magnet (d) lemon juice
8. 8.🔮 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
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) white paper (d) a small bowl
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) a magnet (d) a mirror
11. 11.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
12. 12.⚖️ 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 change it (c) we measure it
13. 13.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) ironing the paper (d) dipping the cotton bud
14. 14.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical
16. 16.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
17. 17.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a magnet (d) a small bowl
19. 19.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
20. 20.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
21. 21.True or false: reading the message is a job for an adult. (a) True (b) False
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) white paper (d) lemon juice
23. 23.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
24. 24.🍋 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
25. 25.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
26. 26.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
27. 27.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
28. 28.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
29. 29.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
30. 30.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) reading the message (c) letting the paper dry (d) dipping the cotton bud
31. 31.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
32. 32.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) plugging in the iron (d) ironing the paper
33. 33.⚖️ 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
34. 34.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the kind of juice (c) the same paper (d) how dark the writing is
36. 36.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
37. 37.⚖️ 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
38. 38.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) green (d) brown
39. 39.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) a magnet (d) yeast
40. 40.True or false: putting the iron away is a job for an adult. (a) True (b) False

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