Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 821 · 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? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
2. 2.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) blue (d) brown
3. 3.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
4. 4.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) letting the paper dry (d) writing the message
5. 5.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) a balloon (d) white paper
6. 6.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) turmeric powder (d) a cotton bud
9. 9.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a small bowl (d) a mirror
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) lemon juice (d) a magnet
13. 13.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
14. 14.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
15. 15.⚖️ 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 kind of juice (c) the iron setting (d) the ironing time
16. 16.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) plugging in the iron (c) writing the message (d) reading the message
17. 17.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) dipping the cotton bud (d) writing the message
18. 18.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
19. 19.True or false: plugging in the iron is a job for an adult. (a) False (b) True
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a mirror (c) a cotton bud (d) lemon juice
21. 21.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
22. 22.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
23. 23.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
24. 24.⚖️ 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) True (b) False
25. 25.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) ironing the paper (d) writing the message
26. 26.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) cutting the lemon
27. 27.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) writing the message
28. 28.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
29. 29.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) lick your fingers (d) skip washing
30. 30.True or false: putting the iron away is a job for an adult. (a) False (b) True
31. 31.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a battery cell (c) turmeric powder (d) a cotton bud
32. 32.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
33. 33.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
34. 34.True or false: plugging in the iron is a job a child can do. (a) True (b) False
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) white paper (d) turmeric powder
36. 36.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
37. 37.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) letting the paper dry (d) plugging in the iron
38. 38.True or false: cutting the lemon is a job a child can do. (a) False (b) True
39. 39.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) cutting the lemon (d) letting the paper dry
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a balloon (c) an adult with an iron (d) white paper

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