Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 935 · 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) ironing the paper (b) reading the message (c) letting the paper dry (d) writing the message
2. 2.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) green (d) white
3. 3.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
4. 4.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
5. 5.⚖️ 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) True (b) False
6. 6.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) paper turns lemony (d) heat adds colour
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) a small bowl (d) a balloon
8. 8.⚖️ 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
9. 9.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
10. 10.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) an adult with an iron (d) yeast
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
13. 13.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
14. 14.True or false: letting the paper dry is a job for an adult. (a) True (b) False
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) a cotton bud (d) white paper
16. 16.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
17. 17.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
18. 18.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) dipping the cotton bud (c) reading the message (d) writing the message
19. 19.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) dipping the cotton bud
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a mirror (d) lemon juice
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) lemon juice (d) a cotton bud
22. 22.⚖️ 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
23. 23.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the kind of juice (c) the same paper (d) the same cotton bud
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
26. 26.True or false: cutting the lemon is a job a child can do. (a) True (b) False
27. 27.⚖️ 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 measure it (c) we keep it the same
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) turmeric powder (c) a mirror (d) a balloon
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
30. 30.⚖️ 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) how dark the writing is (c) the ironing time
31. 31.⚖️ 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
32. 32.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
33. 33.⚖️ 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
34. 34.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) reading the message
35. 35.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) yeast (c) turmeric powder (d) a magnet
37. 37.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
38. 38.True or false: ironing the paper is a job for an adult. (a) False (b) True
39. 39.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
40. 40.⚖️ 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

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