Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 758 · 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: lemon juice is not needed for the secret lemon message. (a) False (b) True
2. 2.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
3. 3.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
4. 4.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) physical (d) musical
5. 5.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
6. 6.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) almost nothing (d) blue words
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) an adult with an iron (d) a magnet
8. 8.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) paper turns lemony (d) the juice scorches first
9. 9.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
10. 10.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
11. 11.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
12. 12.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a small bowl (c) an adult with an iron (d) lemon juice
14. 14.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
15. 15.⚖️ 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
16. 16.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) the youngest child (d) whoever is fastest
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a magnet (c) a small bowl (d) a cotton bud
18. 18.True or false: writing the message is a job for an adult. (a) False (b) True
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
20. 20.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
21. 21.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a magnet (c) a battery cell (d) yeast
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a battery cell (c) a small bowl (d) an adult with an iron
23. 23.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) letting the paper dry (d) cutting the lemon
24. 24.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
25. 25.⚖️ 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) how dark the writing is (c) the same paper
26. 26.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) lemon juice (c) a magnet (d) a balloon
27. 27.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
28. 28.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
29. 29.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) reading the message (d) writing the message
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) yeast (d) white paper
31. 31.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
32. 32.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) writing the message (d) plugging in the iron
33. 33.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same paper (c) the iron setting (d) the same cotton bud
35. 35.⚖️ 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) True (b) False
36. 36.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) letting the paper dry
37. 37.True or false: ironing the paper is a job for an adult. (a) True (b) False
38. 38.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
39. 39.⚖️ 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 keep it the same (c) we change it
40. 40.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) writing turns green (d) the paper floats

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