Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 212 · 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) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
2. 2.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) cutting the lemon (d) reading the message
3. 3.🍋 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
4. 4.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
5. 5.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) white paper (c) a small bowl (d) lemon juice
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
8. 8.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
9. 9.⚖️ 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 keep it the same (c) we change it
10. 10.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a magnet (d) a cotton bud
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) the youngest child (d) whoever is fastest
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) turmeric powder (c) lemon juice (d) a small bowl
15. 15.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
16. 16.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) a small bowl (c) an adult with an iron (d) a cotton bud
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) lemon juice (d) a battery cell
19. 19.⚖️ 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
20. 20.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a balloon (d) turmeric powder
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
22. 22.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) putting the iron away (d) plugging in the iron
23. 23.True or false: reading the message is a job a child can do. (a) False (b) True
24. 24.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
25. 25.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
26. 26.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) a balloon (d) a battery cell
27. 27.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
28. 28.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it can burn skin (d) it is cold
29. 29.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) cutting the lemon
30. 30.⚖️ 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
31. 31.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
32. 32.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) writing the message (d) plugging in the iron
33. 33.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a small bowl (d) a balloon
35. 35.True or false: putting the iron away is a job for an adult. (a) False (b) True
36. 36.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) white paper (d) a mirror
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the same paper (c) the kind of juice (d) the same cotton bud
40. 40.🍋 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

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