Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 419 · 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) writing the message (b) plugging in the iron (c) letting the paper dry (d) dipping the cotton bud
2. 2.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
3. 3.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
4. 4.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) dry juice is see-through (d) the ink is magnetic
5. 5.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
6. 6.⚖️ 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
7. 7.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) dark brown words (d) blue words
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) how dark the writing is (c) the kind of juice (d) the ironing time
9. 9.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
10. 10.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
11. 11.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
12. 12.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
13. 13.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) writing the message (d) plugging in the iron
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) yeast
15. 15.🧺 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 magnet
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
17. 17.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
18. 18.🛟 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
19. 19.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
20. 20.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) heat adds colour (c) paper turns lemony (d) the iron is brown
21. 21.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) reading the message
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the same cotton bud (c) the kind of juice (d) the ironing time
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
25. 25.True or false: white paper is needed for the secret lemon message. (a) False (b) True
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
28. 28.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) putting the iron away (d) plugging in the iron
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a cotton bud (c) lemon juice (d) white paper
30. 30.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
31. 31.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
32. 32.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
33. 33.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) a cotton bud (d) an adult with an iron
35. 35.⚖️ 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
36. 36.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) green (d) brown
37. 37.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
38. 38.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
39. 39.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
40. 40.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) reading the message (c) writing the message (d) dipping the cotton bud

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