Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 677 · 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 a cotton bud for the secret lemon message? (a) not needed (b) needed
2. 2.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) dipping the cotton bud (c) cutting the lemon (d) putting the iron away
3. 3.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) writing the message (d) ironing the paper
4. 4.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is magnetic (d) it is sticky
5. 5.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
6. 6.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) blue (d) green
7. 7.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
8. 8.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
9. 9.True or false: putting the iron away is a job for an adult. (a) False (b) True
10. 10.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
11. 11.⚖️ 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) the same paper (d) the same cotton bud
12. 12.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) lemon juice (d) a battery cell
14. 14.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) reading the message (d) letting the paper dry
15. 15.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) yeast (c) a magnet (d) a balloon
16. 16.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
17. 17.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
18. 18.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a magnet (d) a small bowl
20. 20.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
21. 21.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
23. 23.⚖️ 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 kind of juice (d) the same cotton bud
24. 24.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
25. 25.⚖️ 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 same cotton bud
26. 26.🔍 Which is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) letting the paper dry (d) writing the message
27. 27.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) letting the paper dry (d) ironing the paper
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) a battery cell (d) an adult with an iron
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) a cotton bud (d) a small bowl
31. 31.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
32. 32.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) a balloon (d) a battery cell
33. 33.🔮 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
34. 34.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
35. 35.True or false: a mirror is not needed for the secret lemon message. (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 same paper (b) the kind of juice (c) how dark the writing is
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
38. 38.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
39. 39.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) the iron is brown (d) paper turns lemony
40. 40.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) writing the message (d) dipping the cotton bud

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