Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 441 · 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.⚖️ 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
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a battery cell (d) white paper
3. 3.🍋 Which of these steps is a job for an adult? (a) writing the message (b) plugging in the iron (c) dipping the cotton bud (d) reading the message
4. 4.⚖️ 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 ironing time (c) the kind of juice
5. 5.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) putting the iron away (d) dipping the cotton bud
6. 6.🧺 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) a mirror
7. 7.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
8. 8.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
9. 9.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) a cotton bud (d) white paper
11. 11.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) letting the paper dry (d) cutting the lemon
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) a small bowl (d) a cotton bud
13. 13.🧺 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) a cotton bud (d) yeast
14. 14.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
15. 15.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the ironing time (c) the kind of juice (d) how dark the writing is
17. 17.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) letting the paper dry
18. 18.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
19. 19.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) dipping the cotton bud (d) cutting the lemon
20. 20.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) cutting the lemon
21. 21.True or false: reading the message is a job for an adult. (a) True (b) False
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a magnet (d) white paper
23. 23.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) putting the iron away
24. 24.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
25. 25.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
26. 26.⚖️ 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
27. 27.True or false: putting the iron away is a job a child can do. (a) True (b) False
28. 28.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
30. 30.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
31. 31.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) brown (d) blue
32. 32.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
33. 33.True or false: reading the message is a job a child can do. (a) True (b) False
34. 34.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) yeast (c) a magnet (d) a balloon
36. 36.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) reading the message (d) dipping the cotton bud
37. 37.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
38. 38.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it can burn skin (d) it is sticky
39. 39.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
40. 40.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a balloon (d) yeast

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