Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 366 · 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.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) wash your hands (d) skip washing
2. 2.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) white paper (d) a battery cell
4. 4.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) writing turns green (d) the paper floats
5. 5.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
6. 6.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) cutting the lemon (d) dipping the cotton bud
7. 7.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) lemon juice (d) yeast
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) yeast (d) lemon juice
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) white paper (d) turmeric powder
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
13. 13.🔮 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
14. 14.⚖️ 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 cotton bud (c) the kind of juice
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) a mirror
16. 16.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
17. 17.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) cutting the lemon (d) ironing the paper
18. 18.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
20. 20.True or false: writing the message is a job a child can do. (a) False (b) True
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) lemon juice (d) a cotton bud
22. 22.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) letting the paper dry (d) writing the message
23. 23.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
24. 24.⚖️ 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 keep it the same (c) we measure it
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) a battery cell (d) a cotton bud
26. 26.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
27. 27.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
29. 29.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
30. 30.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
31. 31.True or false: white paper is needed for the secret lemon message. (a) False (b) True
32. 32.True or false: ironing the paper is a job a child can do. (a) True (b) False
33. 33.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
35. 35.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
36. 36.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
37. 37.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) ironing the paper
38. 38.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
39. 39.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) a cotton bud (c) an adult with an iron (d) a small bowl

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