Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 246 · 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 same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
2. 2.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) dry juice is see-through (d) the ink is magnetic
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) turmeric powder (d) an adult with an iron
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
5. 5.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
6. 6.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) cutting the lemon
7. 7.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) it gets darker (d) writing turns green
8. 8.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) almost nothing (d) a rainbow
9. 9.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) brown (d) green
10. 10.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) heat adds colour (c) the iron is brown (d) paper turns lemony
11. 11.⚖️ 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) the iron setting (c) how dark the writing is (d) the ironing time
12. 12.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) plugging in the iron (d) cutting the lemon
13. 13.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
14. 14.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) dipping the cotton bud (d) writing the message
15. 15.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
16. 16.True or false: yeast is needed for the secret lemon message. (a) False (b) True
17. 17.True or false: letting the paper dry is a job for an adult. (a) False (b) True
18. 18.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
19. 19.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
20. 20.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
21. 21.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) a magnet
23. 23.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) ironing the paper
24. 24.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
25. 25.True or false: ironing the paper is a job a child can do. (a) False (b) True
26. 26.⚖️ 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) False (b) True
27. 27.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
28. 28.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) an adult with an iron (d) yeast
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) lemon juice (d) white paper
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) white paper (d) a balloon
33. 33.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
34. 34.True or false: writing the message is a job a child can do. (a) True (b) False
35. 35.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
36. 36.⚖️ 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
37. 37.True or false: putting the iron away is a job a child can do. (a) False (b) True
38. 38.🍋 Which of these steps is a job for an adult? (a) writing the message (b) putting the iron away (c) reading the message (d) dipping the cotton bud
39. 39.⚖️ 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
40. 40.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a battery cell (c) yeast (d) a magnet

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