Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 83 · 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.⚖️ 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 same cotton bud (c) the kind of juice (d) how dark the writing is
2. 2.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
3. 3.⚖️ 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 same paper (c) the same cotton bud (d) the kind of juice
4. 4.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
5. 5.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
7. 7.⚖️ 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
8. 8.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) ironing the paper (c) letting the paper dry (d) reading the message
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
10. 10.True or false: putting the iron away is a job for an adult. (a) True (b) False
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) lemon juice (d) a mirror
13. 13.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) chemical (d) magnetic
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a small bowl (d) turmeric powder
15. 15.⚖️ 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 same cotton bud (c) the kind of juice
16. 16.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
17. 17.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is cold (d) it is sticky
18. 18.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
19. 19.True or false: cutting the lemon is a job for an adult. (a) True (b) False
20. 20.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) a cotton bud (d) a small bowl
22. 22.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
23. 23.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
24. 24.⚖️ 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 ironing time (c) how dark the writing is
25. 25.⚖️ 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
26. 26.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
27. 27.True or false: reading the message is a job a child can do. (a) True (b) False
28. 28.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a battery cell (c) turmeric powder (d) a balloon
29. 29.True or false: plugging in the iron is a job for an adult. (a) True (b) False
30. 30.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) white paper (d) a magnet
32. 32.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
33. 33.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
34. 34.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) letting the paper dry (c) cutting the lemon (d) plugging in the iron
35. 35.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a balloon (c) a magnet (d) a mirror
36. 36.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) letting the paper dry (d) writing the message
37. 37.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) green (d) brown
38. 38.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
39. 39.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
40. 40.True or false: writing the message is a job for an adult. (a) True (b) False

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