Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 568 · 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? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a small bowl (d) a magnet
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) turmeric powder
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) turmeric powder (d) a small bowl
5. 5.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
6. 6.True or false: cutting the lemon is a job a child can do. (a) True (b) False
7. 7.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) plugging in the iron
8. 8.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the iron is brown (d) the juice scorches first
9. 9.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
10. 10.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) writing the message
11. 11.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
12. 12.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) blue (d) green
13. 13.⚖️ 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) the same cotton bud
14. 14.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
15. 15.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) the ink is magnetic (d) it turned into air
16. 16.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) it gets darker (d) the paper floats
17. 17.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) plugging in the iron
18. 18.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
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) False (b) True
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
21. 21.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
22. 22.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) a small bowl (d) turmeric powder
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) an adult with an iron (d) yeast
25. 25.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
26. 26.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a balloon (d) a cotton bud
27. 27.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the same paper (d) the iron setting
29. 29.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
30. 30.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a battery cell (c) a magnet (d) a mirror
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) a balloon (d) lemon juice
32. 32.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
33. 33.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) ironing the paper (d) putting the iron away
34. 34.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
35. 35.True or false: ironing the paper is a job a child can do. (a) True (b) False
36. 36.⚖️ 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 ironing time
37. 37.🔍 Which is the odd one out? (a) letting the paper dry (b) putting the iron away (c) cutting the lemon (d) ironing the paper
38. 38.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
39. 39.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) dipping the cotton bud (d) cutting the lemon
40. 40.True or false: reading the message is a job a child can do. (a) True (b) False

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