Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 434 · 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 what we measure? (a) the same cotton bud (b) how dark the writing is (c) the kind of juice (d) the ironing time
2. 2.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
3. 3.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) ironing the paper (d) dipping the cotton bud
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) lemon juice (d) yeast
5. 5.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
6. 6.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a mirror (d) a small bowl
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
9. 9.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) heat adds colour (d) the iron is brown
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) how dark the writing is (c) the kind of juice (d) the same paper
11. 11.⚖️ 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
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) turmeric powder (d) a mirror
13. 13.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
14. 14.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
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 measure it (b) we change it (c) we keep it the same
16. 16.True or false: ironing the paper is a job for an adult. (a) True (b) False
17. 17.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) plugging in the iron (d) writing the message
18. 18.True or false: yeast is needed for the secret lemon message. (a) True (b) False
19. 19.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) letting the paper dry (d) dipping the cotton bud
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) a magnet (d) an adult with an iron
21. 21.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
22. 22.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
23. 23.True or false: reading the message is a job for an adult. (a) True (b) False
24. 24.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
25. 25.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
26. 26.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) a small bowl (d) an adult with an iron
29. 29.🧺 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) a small bowl (d) a magnet
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we change it (c) we measure it
31. 31.🧺 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 small bowl (d) a battery cell
32. 32.🔮 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
33. 33.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) writing the message (d) letting the paper dry
34. 34.⚖️ 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
35. 35.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) dipping the cotton bud
36. 36.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
37. 37.🍋 Which of these steps is a job a child can do? (a) reading the message (b) ironing the paper (c) plugging in the iron (d) putting the iron away
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 keep it the same (b) we measure it (c) we change it
39. 39.🍋 Which of these steps is a job a child can do? (a) writing the message (b) putting the iron away (c) cutting the lemon (d) plugging in the iron
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) turmeric powder (c) a cotton bud (d) lemon juice

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