Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 391 · 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 is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) putting the iron away (d) reading the message
2. 2.True or false: white paper is needed for the secret lemon message. (a) False (b) True
3. 3.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
4. 4.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
5. 5.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) yeast (d) a small bowl
7. 7.⚖️ 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 keep it the same (c) we measure it
8. 8.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) brown (d) blue
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a mirror (d) lemon juice
10. 10.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
11. 11.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) writing the message (c) dipping the cotton bud (d) reading the message
12. 12.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
13. 13.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) paper turns lemony (d) the juice scorches first
14. 14.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a magnet (d) a small bowl
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
16. 16.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
17. 17.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
18. 18.True or false: letting the paper dry is a job for an adult. (a) False (b) True
19. 19.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) a balloon (d) a cotton bud
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) a balloon
22. 22.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
23. 23.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
24. 24.🛟 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
25. 25.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
26. 26.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the kind of juice (c) how dark the writing is (d) the same cotton bud
28. 28.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
29. 29.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) dipping the cotton bud (d) reading the message
30. 30.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
31. 31.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) plugging in the iron (d) cutting the lemon
32. 32.⚖️ 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 paper (c) the kind of juice
33. 33.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a mirror (c) a cotton bud (d) white paper
35. 35.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) an adult with an iron (d) turmeric powder
38. 38.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) a balloon (d) a mirror
39. 39.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) it turned into air (d) the ink is magnetic
40. 40.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False

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