Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 594 · 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? Which of these is the one thing we change? (a) how dark the writing is (b) the iron setting (c) the kind of juice (d) the ironing time
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
3. 3.⚖️ 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 change it (c) we keep it the same
4. 4.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) reading the message (d) plugging in the iron
5. 5.True or false: reading the message is a job for an adult. (a) True (b) False
6. 6.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
7. 7.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) plugging in the iron (d) letting the paper dry
8. 8.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) dipping the cotton bud (d) cutting the lemon
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) a small bowl (d) a magnet
10. 10.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) an adult with an iron (d) yeast
12. 12.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a magnet (c) white paper (d) a small bowl
14. 14.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) reading the message (d) cutting the lemon
15. 15.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) putting the iron away (c) dipping the cotton bud (d) reading the message
16. 16.🧺 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) white paper
17. 17.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
18. 18.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) a small bowl (d) yeast
20. 20.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is cold (d) it is magnetic
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) an adult with an iron (d) turmeric powder
23. 23.True or false: plugging in the iron is a job for an adult. (a) True (b) False
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) the ink is magnetic (d) it turned into air
25. 25.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
27. 27.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
28. 28.⚖️ 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
29. 29.True or false: plugging in the iron is a job a child can do. (a) False (b) True
30. 30.⚖️ 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
31. 31.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) magnetic (d) chemical
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) an adult with an iron (d) a battery cell
33. 33.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
34. 34.⚖️ 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
35. 35.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) cutting the lemon (d) plugging in the iron
36. 36.⚖️ 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
37. 37.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
38. 38.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
39. 39.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) a mirror (d) a magnet
40. 40.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed

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