Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 289 · 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.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) yeast (d) a cotton bud
3. 3.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the same paper (d) the kind of juice
5. 5.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
6. 6.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
7. 7.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
8. 8.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
9. 9.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
10. 10.⚖️ 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
11. 11.True or false: writing the message is a job a child can do. (a) False (b) True
12. 12.True or false: putting the iron away is a job a child can do. (a) True (b) False
13. 13.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
14. 14.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) yeast (d) lemon juice
15. 15.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
16. 16.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) cutting the lemon (d) ironing the paper
17. 17.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) writing the message (d) reading the message
18. 18.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
19. 19.⚖️ 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
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a mirror (d) white paper
21. 21.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
22. 22.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) writing the message (c) cutting the lemon (d) ironing the paper
23. 23.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) letting the paper dry
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) a cotton bud (d) a small bowl
26. 26.⚖️ 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 cotton bud
27. 27.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) brown (d) blue
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a magnet (d) a cotton bud
29. 29.True or false: reading the message is a job for an adult. (a) True (b) False
30. 30.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) no, it stays brown (d) yes, in the dark
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
33. 33.⚖️ 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
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) white paper (c) an adult with an iron (d) lemon juice
35. 35.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
36. 36.⚖️ 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
37. 37.True or false: cutting the lemon is a job for an adult. (a) True (b) False
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
39. 39.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) paper turns lemony (d) the juice scorches first
40. 40.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) writing the message (d) ironing the paper

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