Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 555 · 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? True or false: the kind of juice is the one thing we change. (a) True (b) False
2. 2.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
4. 4.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the paper ate it (d) the ink is magnetic
5. 5.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) lemon juice (d) an adult with an iron
7. 7.⚖️ 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) the same cotton bud (c) the same paper (d) the kind of juice
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) a balloon (d) lemon juice
9. 9.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) lemon juice (d) yeast
12. 12.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) writing turns green (d) it gets darker
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) a battery cell (d) a small bowl
14. 14.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
15. 15.⚖️ 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
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) white paper (d) a small bowl
17. 17.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) putting the iron away (d) cutting the lemon
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a battery cell (c) a cotton bud (d) a small bowl
19. 19.⚖️ 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
20. 20.True or false: letting the paper dry is a job for an adult. (a) True (b) False
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the kind of juice (c) how dark the writing is (d) the same paper
22. 22.⚖️ 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
23. 23.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) white paper (d) a magnet
25. 25.⚖️ 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 change it (c) we keep it the same
26. 26.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) blue (d) brown
27. 27.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) chemical (d) magnetic
28. 28.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) cutting the lemon (d) writing the message
29. 29.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) plugging in the iron (d) putting the iron away
30. 30.⚖️ 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
31. 31.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice
33. 33.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
34. 34.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
35. 35.⚖️ 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
36. 36.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
37. 37.⚖️ 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 change it (c) we keep it the same
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) lemon juice (d) a mirror
39. 39.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
40. 40.True or false: ironing the paper is a job a child can do. (a) False (b) True

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