Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 194 · 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 not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) a small bowl (d) a magnet
2. 2.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) dipping the cotton bud
3. 3.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) brown (d) white
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) white paper (d) yeast
5. 5.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) dipping the cotton bud (d) reading the message
6. 6.🛟 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
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 iron setting (b) the kind of juice (c) the same paper (d) the same cotton bud
8. 8.True or false: ironing the paper is a job for an adult. (a) True (b) False
9. 9.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) heat adds colour (d) paper turns lemony
10. 10.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) writing the message (d) plugging in the iron
11. 11.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) a small bowl (d) a mirror
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
14. 14.⚖️ 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 same cotton bud
15. 15.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) how dark the writing is (c) the kind of juice (d) the same cotton bud
18. 18.⚖️ 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
19. 19.⚖️ 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
20. 20.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) the paper ate it (d) it turned into air
21. 21.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
22. 22.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
23. 23.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
24. 24.True or false: white paper is needed for the secret lemon message. (a) True (b) False
25. 25.⚖️ 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
26. 26.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
27. 27.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
29. 29.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) ironing the paper (d) dipping the cotton bud
30. 30.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
31. 31.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
33. 33.True or false: reading the message is a job a child can do. (a) False (b) True
34. 34.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
35. 35.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
36. 36.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
37. 37.🔮 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
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a small bowl (d) a mirror
39. 39.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
40. 40.True or false: cutting the lemon is a job a child can do. (a) False (b) True

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