Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 717 · 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.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
2. 2.⚖️ 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
3. 3.True or false: cutting the lemon is a job a child can do. (a) False (b) True
4. 4.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) a magnet (d) a small bowl
5. 5.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) ironing the paper (d) letting the paper dry
6. 6.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) letting the paper dry (d) dipping the cotton bud
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
8. 8.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
9. 9.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) putting the iron away (d) dipping the cotton bud
10. 10.⚖️ 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) how dark the writing is (c) the kind of juice (d) the ironing time
11. 11.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
12. 12.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) yeast (d) a cotton bud
14. 14.True or false: putting the iron away is a job for an adult. (a) False (b) True
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
16. 16.🧺 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) lemon juice (d) a mirror
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a balloon (d) an adult with an iron
18. 18.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
19. 19.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
20. 20.True or false: plugging in the iron is a job a child can do. (a) False (b) True
21. 21.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
22. 22.True or false: white paper is needed for the secret lemon message. (a) False (b) True
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
25. 25.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) lemon juice (c) an adult with an iron (d) a small bowl
27. 27.🍋 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
28. 28.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) plugging in the iron (d) dipping the cotton bud
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the kind of juice (c) the same paper (d) how dark the writing is
30. 30.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
31. 31.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) dark brown words (d) blue words
32. 32.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
33. 33.⚖️ 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
34. 34.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
35. 35.⚖️ 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 measure it (c) we keep it the same
36. 36.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
37. 37.⚖️ 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
38. 38.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
39. 39.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a balloon (c) a mirror (d) a battery cell
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a magnet (c) a small bowl (d) white paper

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