Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 182 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) yeast (c) lemon juice (d) a small bowl
2. 2.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) ironing the paper (d) writing the message
3. 3.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
4. 4.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
5. 5.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) plugging in the iron (d) putting the iron away
6. 6.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) no, it stays brown (d) yes, if shaken
7. 7.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
8. 8.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) rub your eyes (d) skip washing
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
10. 10.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a cotton bud (d) a battery cell
12. 12.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
13. 13.True or false: plugging in the iron is a job a child can do. (a) True (b) False
14. 14.🔮 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
15. 15.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) it turned into air (d) the paper ate it
16. 16.⚖️ 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
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
18. 18.⚖️ 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) True (b) False
19. 19.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) lemon juice (d) a mirror
21. 21.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) reading the message (d) putting the iron away
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) an adult with an iron (c) white paper (d) a cotton bud
23. 23.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
24. 24.True or false: ironing the paper is a job a child can do. (a) False (b) True
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a balloon (d) lemon juice
26. 26.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) reading the message (d) letting the paper dry
27. 27.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
28. 28.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) reading the message (c) plugging in the iron (d) cutting the lemon
29. 29.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) chemical (d) physical
30. 30.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) a cotton bud (d) a magnet
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) a magnet (d) lemon juice
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a battery cell (d) an adult with an iron
34. 34.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
35. 35.⚖️ 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 ironing time (c) how dark the writing is (d) the kind of juice
36. 36.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) lemon juice (d) a battery cell
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) yeast (d) turmeric powder
40. 40.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True

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