Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 455 · 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.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, in the dark (d) yes, if shaken
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
3. 3.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) a magnet (d) lemon juice
5. 5.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is cold (d) it is sticky
6. 6.True or false: cutting the lemon is a job for an adult. (a) False (b) True
7. 7.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
8. 8.True or false: white paper is needed for the secret lemon message. (a) False (b) True
9. 9.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) reading the message (d) cutting the lemon
10. 10.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) writing the message (d) plugging in the iron
11. 11.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
12. 12.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
13. 13.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
15. 15.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
16. 16.True or false: plugging in the iron is a job a child can do. (a) False (b) True
17. 17.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) letting the paper dry (c) reading the message (d) dipping the cotton bud
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) lemon juice (d) yeast
19. 19.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
20. 20.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
21. 21.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) reading the message
22. 22.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) the iron setting (d) how dark the writing is
24. 24.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
25. 25.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) dipping the cotton bud
26. 26.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
27. 27.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
28. 28.⚖️ 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) True (b) False
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
30. 30.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) cutting the lemon (d) reading the message
31. 31.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
32. 32.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) dipping the cotton bud (d) writing the message
33. 33.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
34. 34.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
35. 35.True or false: putting the iron away is a job for an adult. (a) True (b) False
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a cotton bud (c) lemon juice (d) an adult with an iron
37. 37.⚖️ 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 iron setting
38. 38.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
39. 39.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) turmeric powder (c) a magnet (d) a balloon
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same

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