Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 800 · 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.🧺 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) yeast
2. 2.⚖️ 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
3. 3.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) ironing the paper (d) cutting the lemon
4. 4.True or false: putting the iron away is a job a child can do. (a) False (b) True
5. 5.🍋 Secret message: who does this step — cutting the lemon? (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) lemon juice (b) a cotton bud (c) an adult with an iron (d) a balloon
7. 7.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) dipping the cotton bud
8. 8.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) ironing the paper
9. 9.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) a battery cell (d) lemon juice
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) turmeric powder (c) white paper (d) lemon juice
14. 14.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled
15. 15.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) it turned into air (d) the paper ate it
16. 16.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) yeast (c) a battery cell (d) a balloon
17. 17.True or false: reading the message is a job a child can do. (a) False (b) True
18. 18.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) dipping the cotton bud (d) plugging in the iron
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the iron setting (c) the kind of juice (d) how dark the writing is
21. 21.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
22. 22.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
23. 23.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) any child (d) the youngest child
24. 24.True or false: cutting the lemon is a job a child can do. (a) True (b) False
25. 25.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a battery cell (c) lemon juice (d) white paper
27. 27.True or false: white paper is needed for the secret lemon message. (a) True (b) False
28. 28.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) cutting the lemon
29. 29.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
30. 30.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a balloon (c) an adult with an iron (d) a cotton bud
32. 32.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
33. 33.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) writing the message (d) cutting the lemon
34. 34.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
35. 35.⚖️ 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) False (b) True
36. 36.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
37. 37.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
38. 38.🛟 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
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) a balloon (d) a cotton bud
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it

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