Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 298 · 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.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) the paper ate it (d) it turned into air
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) lemon juice (d) a balloon
3. 3.⚖️ 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 change it (c) we measure it
4. 4.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
5. 5.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
6. 6.True or false: white paper is needed for the secret lemon message. (a) True (b) False
7. 7.⚖️ 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
8. 8.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) putting the iron away (c) ironing the paper (d) cutting the lemon
9. 9.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
10. 10.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
11. 11.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
12. 12.⚖️ 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 change it (c) we keep it the same
13. 13.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) a mirror (d) white paper
14. 14.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
15. 15.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) plugging in the iron
16. 16.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) turmeric powder (d) a small bowl
18. 18.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
20. 20.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
21. 21.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) putting the iron away (d) ironing the paper
22. 22.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
23. 23.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) a magnet (d) an adult with an iron
24. 24.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
25. 25.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) physical (d) magnetic
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 — writing the message? (a) an adult does it (b) a child can do it
28. 28.True or false: reading the message is a job for an adult. (a) True (b) False
29. 29.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) writing the message (c) reading the message (d) letting the paper dry
30. 30.⚖️ 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 kind of juice (c) the ironing time (d) the same paper
31. 31.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
32. 32.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
33. 33.⚖️ 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) the same paper (c) how dark the writing is
34. 34.⚖️ 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) True (b) False
35. 35.True or false: plugging in the iron is a job a child can do. (a) True (b) False
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) turmeric powder (d) a mirror
37. 37.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
38. 38.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) turmeric powder
40. 40.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) dipping the cotton bud (d) reading the message

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