Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 846 · 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.True or false: white paper is needed for the secret lemon message. (a) False (b) True
2. 2.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
3. 3.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) brown (d) green
4. 4.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a mirror (c) turmeric powder (d) a battery cell
5. 5.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) a battery cell (d) yeast
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 same cotton bud (b) the same paper (c) the iron setting (d) the kind of juice
8. 8.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) plugging in the iron
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) turmeric powder (c) an adult with an iron (d) a small bowl
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 keep it the same (b) we measure it (c) we change it
11. 11.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
12. 12.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) a rainbow (d) dark brown words
13. 13.⚖️ 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 paper
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a magnet (c) a small bowl (d) a cotton bud
15. 15.True or false: plugging in the iron is a job for an adult. (a) True (b) False
16. 16.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) the paper ate it (d) dry juice is see-through
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) a mirror (d) lemon juice
18. 18.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
19. 19.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
20. 20.True or false: yeast is needed for the secret lemon message. (a) True (b) False
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) yeast (d) a cotton bud
22. 22.⚖️ 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 same cotton bud (c) how dark the writing is
23. 23.True or false: putting the iron away is a job for an adult. (a) False (b) True
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) white paper (d) a battery cell
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) yeast (c) a balloon (d) turmeric powder
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
27. 27.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a balloon (c) a battery cell (d) a magnet
28. 28.🧺 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
29. 29.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the same paper (c) the ironing time (d) how dark the writing is
31. 31.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) writing the message
32. 32.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it can burn skin (d) it is magnetic
33. 33.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
34. 34.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
36. 36.⚖️ 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
37. 37.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
38. 38.True or false: ironing the paper is a job a child can do. (a) True (b) False
39. 39.True or false: ironing the paper is a job for an adult. (a) False (b) True
40. 40.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical

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