Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 757 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
2. 2.🧺 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 cotton bud (d) a balloon
3. 3.⚖️ 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
4. 4.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) an adult with an iron (c) lemon juice (d) white paper
6. 6.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) the paper floats (d) writing turns green
7. 7.True or false: writing the message is a job for an adult. (a) True (b) False
8. 8.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) reading the message (d) letting the paper dry
9. 9.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) cutting the lemon (d) putting the iron away
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) white paper (c) turmeric powder (d) a balloon
11. 11.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) letting the paper dry (d) dipping the cotton bud
12. 12.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
13. 13.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) ironing the paper (d) putting the iron away
14. 14.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) yes, in the dark (d) no, it stays brown
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
16. 16.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
17. 17.True or false: reading the message is a job for an adult. (a) False (b) True
18. 18.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
19. 19.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) a balloon (d) turmeric powder
21. 21.⚖️ 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 change it (c) we measure it
22. 22.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) lemon juice (d) white paper
24. 24.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) cutting the lemon (c) dipping the cotton bud (d) writing the message
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the kind of juice (c) the same cotton bud (d) how dark the writing is
26. 26.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) yeast (c) a cotton bud (d) white paper
28. 28.True or false: writing the message is a job a child can do. (a) True (b) False
29. 29.⚖️ 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 change it (c) we keep it the same
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a battery cell (c) a cotton bud (d) a small bowl
31. 31.🧺 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) turmeric powder (d) lemon juice
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) turmeric powder (d) lemon juice
33. 33.🍋 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) plugging in the iron
34. 34.True or false: ironing the paper is a job a child can do. (a) False (b) True
35. 35.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
36. 36.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) a battery cell
38. 38.True or false: putting the iron away is a job for an adult. (a) False (b) True
39. 39.🍋 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
40. 40.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed

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