Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 461 · 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: turmeric powder is needed for the secret lemon message. (a) True (b) False
2. 2.⚖️ 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 measure it (c) we keep it the same
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) white paper (d) lemon juice
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a magnet (d) a cotton bud
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the same paper (d) the same cotton bud
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
7. 7.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
8. 8.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a balloon (c) a magnet (d) turmeric powder
9. 9.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) putting the iron away (d) cutting the lemon
10. 10.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) heat adds colour (d) paper turns lemony
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.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
13. 13.True or false: ironing the paper is a job a child can do. (a) False (b) True
14. 14.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
15. 15.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) letting the paper dry (d) reading the message
16. 16.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the ironing time (d) the iron setting
18. 18.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
19. 19.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) writing the message (d) cutting the lemon
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) a magnet (d) an adult with an iron
21. 21.True or false: reading the message is a job for an adult. (a) True (b) False
22. 22.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
23. 23.⚖️ 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) False (b) True
24. 24.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
25. 25.True or false: white paper is needed for the secret lemon message. (a) False (b) True
26. 26.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
27. 27.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
28. 28.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
29. 29.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
30. 30.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
31. 31.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
32. 32.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) reading the message (d) dipping the cotton bud
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a cotton bud (d) yeast
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) a small bowl (c) white paper (d) an adult with an iron
36. 36.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) dipping the cotton bud (d) letting the paper dry
37. 37.🛟 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
38. 38.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) letting the paper dry (d) dipping the cotton bud
39. 39.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
40. 40.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) plugging in the iron

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