Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 611 · 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.True or false: writing the message is a job a child can do. (a) False (b) True
2. 2.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
3. 3.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
4. 4.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) white paper (d) turmeric powder
6. 6.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the iron setting (d) the same cotton bud
8. 8.🧺 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) a balloon (d) white paper
9. 9.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) the juice scorches first (d) heat adds colour
10. 10.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) writing the message (d) cutting the lemon
11. 11.True or false: yeast is needed for the secret lemon message. (a) False (b) True
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) yeast (c) lemon juice (d) a small bowl
13. 13.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) cutting the lemon
14. 14.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
16. 16.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a mirror (d) an adult with an iron
18. 18.⚖️ 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 measure it (c) we change it
19. 19.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
20. 20.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) a cotton bud (d) a small bowl
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a mirror (c) lemon juice (d) a cotton bud
23. 23.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) the ink is magnetic (d) it turned into air
25. 25.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) blue (d) white
26. 26.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) letting the paper dry (d) putting the iron away
27. 27.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
30. 30.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) a small bowl (d) a battery cell
31. 31.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) a small bowl (d) lemon juice
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
34. 34.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
35. 35.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) rub your eyes (d) wash your hands
36. 36.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) dipping the cotton bud (d) reading the message
37. 37.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) a balloon (d) a mirror
38. 38.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) letting the paper dry (d) dipping the cotton bud
39. 39.True or false: reading the message is a job for an adult. (a) True (b) False
40. 40.True or false: cutting the lemon is a job a child can do. (a) True (b) False

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