Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 708 · 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 is the odd one out? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) ironing the paper
2. 2.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a mirror (d) a magnet
3. 3.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
4. 4.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
5. 5.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
6. 6.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) putting the iron away (d) reading the message
7. 7.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
8. 8.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the juice scorches first (d) the iron is brown
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
10. 10.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
11. 11.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) physical (d) magnetic
12. 12.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) reading the message
13. 13.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) writing the message
14. 14.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
16. 16.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) reading the message (d) dipping the cotton bud
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) yeast (d) white paper
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the iron setting (c) the kind of juice (d) the ironing time
19. 19.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) whoever is fastest (d) any child
20. 20.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
21. 21.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) reading the message
22. 22.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) an adult with an iron (d) a magnet
25. 25.True or false: white paper is needed for the secret lemon message. (a) False (b) True
26. 26.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) white paper (d) a cotton bud
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) a battery cell (d) a mirror
29. 29.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
30. 30.True or false: cutting the lemon is a job a child can do. (a) True (b) False
31. 31.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
32. 32.True or false: writing the message is a job for an adult. (a) False (b) True
33. 33.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
35. 35.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
36. 36.🔮 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
37. 37.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a small bowl (d) a magnet
38. 38.True or false: reading the message is a job a child can do. (a) False (b) True
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) yeast (c) an adult with an iron (d) a cotton bud
40. 40.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) blue (d) brown

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