Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 483 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a small bowl (d) a battery cell
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
3. 3.True or false: letting the paper dry is a job a child can do. (a) False (b) True
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) a battery cell (d) lemon juice
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the same cotton bud (c) how dark the writing is (d) the ironing time
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) a cotton bud (d) yeast
7. 7.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) dipping the cotton bud (d) writing the message
8. 8.⚖️ 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 measure it (c) we change it
9. 9.⚖️ 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
10. 10.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
11. 11.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) putting the iron away (d) cutting the lemon
12. 12.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
14. 14.🍋 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
15. 15.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) lemon juice (d) white paper
17. 17.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) plugging in the iron (d) writing the message
18. 18.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
21. 21.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
22. 22.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
23. 23.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) the iron is brown (d) heat adds colour
24. 24.⚖️ 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 same cotton bud (c) how dark the writing is
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a cotton bud (d) a battery cell
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a balloon (c) an adult with an iron (d) a cotton bud
27. 27.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) dipping the cotton bud (d) writing the message
28. 28.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the ironing time
30. 30.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
31. 31.True or false: plugging in the iron is a job a child can do. (a) True (b) False
32. 32.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
33. 33.🔮 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
34. 34.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
35. 35.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
36. 36.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) white paper (d) a magnet
38. 38.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) a small bowl (d) a balloon
40. 40.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed

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