Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 701 · 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 of these is needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a balloon (d) a mirror
2. 2.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) a cotton bud (d) a battery cell
4. 4.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
5. 5.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
6. 6.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) turmeric powder (d) a small bowl
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) an adult with an iron (d) yeast
9. 9.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
10. 10.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
11. 11.True or false: cutting the lemon is a job for an adult. (a) True (b) False
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.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
14. 14.⚖️ 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 keep it the same (c) we change it
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) white paper (c) a cotton bud (d) lemon juice
16. 16.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) white paper (d) turmeric powder
17. 17.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) dipping the cotton bud (d) putting the iron away
18. 18.⚖️ 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
19. 19.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
21. 21.⚖️ 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
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) yeast (d) white paper
23. 23.🧺 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) an adult with an iron
24. 24.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) it gets darker (d) writing turns green
25. 25.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) paper turns lemony (d) the iron is brown
26. 26.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
28. 28.True or false: letting the paper dry is a job for an adult. (a) True (b) False
29. 29.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
30. 30.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
31. 31.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
32. 32.True or false: cutting the lemon is a job a child can do. (a) True (b) False
33. 33.⚖️ 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 measure it (c) we change it
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) how dark the writing is (c) the same paper (d) the kind of juice
35. 35.⚖️ 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 ironing time (c) the kind of juice
36. 36.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
38. 38.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
39. 39.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) reading the message
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice

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