Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 554 · 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.⚖️ 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 same paper (c) the ironing time (d) the kind of juice
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
3. 3.⚖️ 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) how dark the writing is (c) the iron setting
4. 4.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) yeast (c) an adult with an iron (d) a cotton bud
6. 6.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
9. 9.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) plugging in the iron (d) putting the iron away
10. 10.True or false: cutting the lemon is a job for an adult. (a) False (b) True
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a magnet (d) an adult with an iron
12. 12.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a battery cell (c) a small bowl (d) a magnet
13. 13.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) a battery cell
15. 15.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) plugging in the iron (d) putting the iron away
16. 16.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
17. 17.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the juice scorches first (d) the iron is brown
18. 18.⚖️ 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) True (b) False
19. 19.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
20. 20.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is sticky (d) it is cold
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
22. 22.🧺 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 mirror (d) lemon juice
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) turmeric powder (d) a battery cell
24. 24.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) dipping the cotton bud (d) letting the paper dry
25. 25.True or false: ironing the paper is a job a child can do. (a) False (b) True
26. 26.True or false: writing the message is a job a child can do. (a) False (b) True
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.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) ironing the paper
29. 29.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
30. 30.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a small bowl (d) turmeric powder
32. 32.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
33. 33.🍋 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
34. 34.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
35. 35.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
36. 36.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) ironing the paper (d) letting the paper dry
37. 37.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
38. 38.True or false: reading the message is a job a child can do. (a) True (b) False
39. 39.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) putting the iron away
40. 40.True or false: plugging in the iron is a job a child can do. (a) False (b) True

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