Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 566 · 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.🔮 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
2. 2.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) ironing the paper (d) reading the message
3. 3.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) physical (d) magnetic
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) a magnet (d) a small bowl
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) yeast
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
7. 7.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
8. 8.🔍 Which is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) a small bowl (d) a cotton bud
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
11. 11.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
12. 12.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
13. 13.True or false: white paper is needed for the secret lemon message. (a) False (b) True
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
16. 16.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
17. 17.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
18. 18.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a cotton bud (d) a small bowl
20. 20.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) ironing the paper (d) putting the iron away
21. 21.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) ironing the paper
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a battery cell (d) white paper
23. 23.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a cotton bud (d) white paper
25. 25.🧺 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 magnet (d) white paper
26. 26.True or false: ironing the paper is a job a child can do. (a) True (b) False
27. 27.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) dipping the cotton bud (d) reading the message
28. 28.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
30. 30.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
32. 32.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
33. 33.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the ironing time (c) the same cotton bud (d) how dark the writing is
35. 35.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
36. 36.⚖️ 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
37. 37.⚖️ 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
38. 38.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) plugging in the iron (d) dipping the cotton bud
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
40. 40.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) heat adds colour (d) paper turns lemony

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