Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 606 · 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.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
2. 2.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
3. 3.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
4. 4.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green
5. 5.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
6. 6.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) white paper (d) a mirror
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
9. 9.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) yeast (c) a battery cell (d) a mirror
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 measure it (b) we keep it the same (c) we change it
11. 11.True or false: ironing the paper is a job a child can do. (a) False (b) True
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
13. 13.🍋 Secret message: who does this step — plugging in the iron? (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 ironing time”? (a) we measure it (b) we change it (c) we keep it the same
15. 15.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) turmeric powder (d) lemon juice
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
18. 18.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
19. 19.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) physical (d) chemical
20. 20.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) white paper (c) a small bowl (d) lemon juice
22. 22.⚖️ 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 same cotton bud
23. 23.True or false: yeast is needed for the secret lemon message. (a) False (b) True
24. 24.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the iron setting (c) the kind of juice (d) the ironing time
26. 26.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
27. 27.🍋 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) plugging in the iron
28. 28.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) putting the iron away (d) writing the message
29. 29.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
30. 30.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) ironing the paper (d) writing the message
31. 31.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) a battery cell (d) yeast
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
33. 33.⚖️ 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
34. 34.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
37. 37.True or false: plugging in the iron is a job a child can do. (a) True (b) False
38. 38.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) white paper (d) an adult with an iron
40. 40.True or false: plugging in the iron is a job for an adult. (a) True (b) False

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