Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 27 · 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 needed for the secret lemon message? (a) lemon juice (b) a balloon (c) yeast (d) a battery cell
2. 2.🍋 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
3. 3.🍋 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
4. 4.⚖️ 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 cotton bud
5. 5.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) ironing the paper (d) cutting the lemon
6. 6.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) putting the iron away
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) a battery cell (d) lemon juice
8. 8.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) blue words (d) a rainbow
9. 9.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
10. 10.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
11. 11.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) cutting the lemon
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
13. 13.True or false: ironing the paper is a job for an adult. (a) True (b) False
14. 14.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is magnetic (d) it is sticky
15. 15.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) letting the paper dry (d) ironing the paper
16. 16.True or false: writing the message is a job for an adult. (a) False (b) True
17. 17.🧺 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 magnet (d) a small bowl
18. 18.⚖️ 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
19. 19.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
21. 21.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a balloon (c) a battery cell (d) a mirror
22. 22.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
23. 23.🍋 Which of these steps is a job a child can do? (a) writing the message (b) cutting the lemon (c) ironing the paper (d) putting the iron away
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) yeast (c) lemon juice (d) a small bowl
26. 26.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
27. 27.True or false: cutting the lemon is a job a child can do. (a) True (b) False
28. 28.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) ironing the paper (d) plugging in the iron
29. 29.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) dipping the cotton bud (d) cutting the lemon
30. 30.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) dipping the cotton bud (d) letting the paper dry
31. 31.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) wash your hands (d) skip washing
32. 32.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) letting the paper dry (d) putting the iron away
33. 33.⚖️ 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
34. 34.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
35. 35.True or false: reading the message is a job for an adult. (a) True (b) False
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) yeast (d) a cotton bud
38. 38.⚖️ 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 ironing time (c) how dark the writing is
39. 39.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) it gets darker (d) the paper floats
40. 40.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False

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