Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 399 · 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.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) ironing the paper (d) plugging in the iron
2. 2.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) an adult with an iron (d) turmeric powder
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a small bowl (d) a balloon
5. 5.True or false: plugging in the iron is a job a child can do. (a) True (b) False
6. 6.🍋 Secret message: who does this step — dipping the cotton bud? (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? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the iron setting
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) yeast (d) an adult with an iron
10. 10.⚖️ 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 keep it the same (c) we measure it
11. 11.True or false: ironing the paper is a job a child can do. (a) True (b) False
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) lemon juice (d) a magnet
13. 13.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) turmeric powder (d) white paper
15. 15.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
16. 16.⚖️ 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) how dark the writing is (d) the iron setting
17. 17.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) white paper (d) turmeric powder
18. 18.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) paper turns lemony (d) the juice scorches first
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a mirror (d) white paper
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
21. 21.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
22. 22.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) writing the message
23. 23.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
24. 24.⚖️ 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 measure it (c) we keep it the same
25. 25.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) the paper ate it (d) dry juice is see-through
26. 26.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) ironing the paper
27. 27.⚖️ 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 keep it the same (c) we change it
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
29. 29.True or false: ironing the paper is a job for an adult. (a) False (b) True
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) yeast
31. 31.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) musical (d) physical
32. 32.🛟 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
33. 33.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) writing the message (c) dipping the cotton bud (d) letting the paper dry
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the iron setting (c) how dark the writing is (d) the same cotton bud
35. 35.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same paper (c) how dark the writing is
37. 37.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
38. 38.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
39. 39.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
40. 40.True or false: white paper is needed for the secret lemon message. (a) True (b) False

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