Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 301 · 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: a battery cell is needed for the secret lemon message. (a) False (b) True
2. 2.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) plugging in the iron
3. 3.True or false: yeast is needed for the secret lemon message. (a) True (b) False
4. 4.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) ironing the paper (d) letting the paper dry
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
6. 6.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
7. 7.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) blue (d) brown
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) an adult with an iron (d) a small bowl
9. 9.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
10. 10.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
11. 11.True or false: putting the iron away is a job for an adult. (a) True (b) False
12. 12.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
13. 13.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) dipping the cotton bud
14. 14.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) the youngest child (d) whoever is fastest
15. 15.⚖️ 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) False (b) True
16. 16.⚖️ 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
17. 17.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
19. 19.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) lemon juice (d) a balloon
20. 20.⚖️ 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
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a mirror (c) a battery cell (d) turmeric powder
22. 22.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
23. 23.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
24. 24.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
25. 25.🍋 Which of these steps is a job a child can do? (a) writing the message (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
26. 26.🧺 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 mirror (d) lemon juice
27. 27.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
28. 28.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) a battery cell (d) a magnet
29. 29.True or false: ironing the paper is a job for an adult. (a) False (b) True
30. 30.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) plugging in the iron (d) putting the iron away
31. 31.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
32. 32.True or false: ironing the paper is a job a child can do. (a) True (b) False
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) yeast (c) a small bowl (d) an adult with an iron
34. 34.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
35. 35.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) letting the paper dry (d) ironing the paper
36. 36.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
37. 37.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
38. 38.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
39. 39.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a balloon (d) a small bowl

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