Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 384 · 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.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
2. 2.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
3. 3.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) putting the iron away (d) ironing the paper
4. 4.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
5. 5.⚖️ 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 change it (c) we measure it
6. 6.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
7. 7.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
8. 8.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
9. 9.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
11. 11.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
12. 12.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) plugging in the iron
13. 13.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) ironing the paper
14. 14.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) putting the iron away (c) plugging in the iron (d) ironing the paper
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
16. 16.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
17. 17.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a battery cell (d) white paper
19. 19.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) dipping the cotton bud (d) plugging in the iron
20. 20.⚖️ 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
21. 21.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
22. 22.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) a magnet (d) lemon juice
23. 23.🧺 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
24. 24.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the ironing time (c) the same cotton bud (d) the iron setting
26. 26.⚖️ 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
27. 27.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) musical (d) magnetic
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
29. 29.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) cutting the lemon
30. 30.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
31. 31.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
32. 32.True or false: reading the message is a job for an adult. (a) False (b) True
33. 33.True or false: ironing the paper is a job a child can do. (a) False (b) True
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) turmeric powder (d) an adult with an iron
35. 35.⚖️ 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
36. 36.🔮 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
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a magnet (d) lemon juice
38. 38.True or false: cutting the lemon is a job for an adult. (a) True (b) False
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
40. 40.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) putting the iron away (c) writing the message (d) dipping the cotton bud

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