Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 749 · 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 what we measure? (a) the same cotton bud (b) the iron setting (c) the ironing time (d) how dark the writing is
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
3. 3.⚖️ 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 change it (c) we keep it the same
4. 4.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) cutting the lemon (c) letting the paper dry (d) writing the message
5. 5.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) a magnet (d) a mirror
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
7. 7.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) dipping the cotton bud (d) writing the message
8. 8.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
10. 10.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
11. 11.True or false: plugging in the iron is a job for an adult. (a) False (b) True
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
13. 13.⚖️ 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
14. 14.⚖️ 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) how dark the writing is (c) the iron setting
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
16. 16.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
17. 17.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
18. 18.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) reading the message
19. 19.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) writing the message (d) cutting the lemon
20. 20.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
21. 21.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) musical (d) magnetic
22. 22.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
23. 23.⚖️ 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
24. 24.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
25. 25.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
26. 26.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) cutting the lemon (d) ironing the paper
27. 27.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
29. 29.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
30. 30.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) lemon juice (d) yeast
31. 31.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) dark brown words (d) almost nothing
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) a cotton bud (d) an adult with an iron
33. 33.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
34. 34.🔮 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
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) lemon juice (d) a magnet
36. 36.🧺 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) a balloon
37. 37.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
39. 39.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) lemon juice (d) white paper

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