Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 686 · 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: lemon juice is needed for the secret lemon message. (a) False (b) True
2. 2.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) letting the paper dry
3. 3.🔮 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
4. 4.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a battery cell (d) a cotton bud
6. 6.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
7. 7.⚖️ 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 keep it the same (c) we change it
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the ironing time (c) the kind of juice (d) the same paper
9. 9.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
10. 10.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
11. 11.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
13. 13.True or false: letting the paper dry is a job for an adult. (a) False (b) True
14. 14.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) letting the paper dry (c) putting the iron away (d) ironing the paper
15. 15.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) putting the iron away (d) letting the paper dry
16. 16.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) magnetic (d) musical
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) a magnet (d) a small bowl
18. 18.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) putting the iron away (d) dipping the cotton bud
19. 19.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
20. 20.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a battery cell (c) a balloon (d) turmeric powder
21. 21.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
22. 22.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a cotton bud (c) an adult with an iron (d) lemon juice
24. 24.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) the youngest child (d) any child
25. 25.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
26. 26.⚖️ 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
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) yeast (c) a small bowl (d) a cotton bud
28. 28.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) a cotton bud (d) a magnet
30. 30.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
31. 31.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
32. 32.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) ironing the paper
33. 33.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) rub your eyes (d) skip washing
34. 34.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) plugging in the iron (d) ironing the paper
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) white paper (c) a small bowl (d) a cotton bud
36. 36.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) ironing the paper (d) letting the paper dry
37. 37.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
38. 38.⚖️ 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 keep it the same (c) we measure it
39. 39.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
40. 40.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) reading the message (d) putting the iron away

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