Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 957 · 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.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
3. 3.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) a cotton bud (d) a battery cell
4. 4.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
6. 6.⚖️ 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
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) rub your eyes (d) wash your hands
8. 8.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
9. 9.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
10. 10.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is magnetic (d) it is cold
11. 11.True or false: yeast is needed for the secret lemon message. (a) False (b) True
12. 12.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
13. 13.🍋 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) dipping the cotton bud
14. 14.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) a balloon (d) yeast
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) chemical (d) physical
16. 16.🧺 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 magnet
17. 17.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) turmeric powder (c) an adult with an iron (d) a cotton bud
19. 19.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
20. 20.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
21. 21.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) letting the paper dry (d) cutting the lemon
22. 22.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
24. 24.🔮 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
25. 25.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) letting the paper dry (d) reading the message
26. 26.⚖️ 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 iron setting (d) the same paper
27. 27.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
28. 28.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
29. 29.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
31. 31.True or false: writing the message is a job for an adult. (a) False (b) True
32. 32.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) putting the iron away (d) reading the message
33. 33.True or false: white paper is needed for the secret lemon message. (a) False (b) True
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a battery cell (d) a small bowl
35. 35.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, in the dark (d) yes, if cooled
36. 36.⚖️ 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 same cotton bud
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) yeast (c) lemon juice (d) a cotton bud
38. 38.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
39. 39.⚖️ 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
40. 40.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True

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