Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 887 · 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? True or false: the kind of juice is what we measure. (a) True (b) False
2. 2.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
3. 3.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) a balloon (d) an adult with an iron
5. 5.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
6. 6.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) ironing the paper
7. 7.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
8. 8.True or false: letting the paper dry is a job a child can do. (a) False (b) True
9. 9.🛟 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
10. 10.⚖️ 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
11. 11.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) letting the paper dry (d) putting the iron away
12. 12.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
13. 13.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
14. 14.🛟 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
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) chemical (d) physical
16. 16.True or false: ironing the paper is a job for an adult. (a) False (b) True
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) an adult with an iron (d) turmeric powder
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same cotton bud (c) the iron setting (d) the kind of juice
19. 19.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
20. 20.True or false: yeast is needed for the secret lemon message. (a) False (b) True
21. 21.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, in the dark (d) yes, if cooled
22. 22.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) a mirror
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a cotton bud (d) a balloon
25. 25.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) cutting the lemon (c) ironing the paper (d) putting the iron away
26. 26.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) turmeric powder (d) a magnet
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
28. 28.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
29. 29.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) cutting the lemon (d) ironing the paper
30. 30.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) ironing the paper (d) plugging in the iron
31. 31.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
32. 32.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
33. 33.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) dark brown words (d) a rainbow
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) a small bowl (d) lemon juice
35. 35.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) putting the iron away (d) letting the paper dry
36. 36.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
37. 37.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
38. 38.⚖️ 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
39. 39.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) turmeric powder (c) a small bowl (d) lemon juice

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