Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 952 · 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.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) cutting the lemon (d) letting the paper dry
2. 2.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) green (d) brown
3. 3.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) ironing the paper (d) reading the message
4. 4.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a battery cell (d) lemon juice
6. 6.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) lemon juice (d) a cotton bud
8. 8.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
9. 9.⚖️ 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
10. 10.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) cutting the lemon (c) putting the iron away (d) plugging in the iron
11. 11.⚖️ 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
12. 12.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
13. 13.True or false: cutting the lemon is a job a child can do. (a) True (b) False
14. 14.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) lemon juice (d) a balloon
16. 16.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
17. 17.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) the paper floats (d) writing turns green
18. 18.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) ironing the paper (d) cutting the lemon
19. 19.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
20. 20.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
21. 21.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) yeast (d) an adult with an iron
23. 23.🧺 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 battery cell
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) turmeric powder (d) lemon juice
27. 27.True or false: ironing the paper is a job for an adult. (a) False (b) True
28. 28.⚖️ 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 same cotton bud (c) how dark the writing is (d) the iron setting
29. 29.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it can burn skin (d) it is sticky
30. 30.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) white paper (d) a mirror
32. 32.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) writing the message
33. 33.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
34. 34.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
35. 35.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
36. 36.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) dipping the cotton bud (d) cutting the lemon
37. 37.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
38. 38.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
39. 39.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) any child (d) whoever is fastest
40. 40.⚖️ 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

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