Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 778 · 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.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) it turned into air (d) the paper ate it
2. 2.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) a small bowl (d) lemon juice
4. 4.True or false: cutting the lemon is a job for an adult. (a) True (b) False
5. 5.🍋 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) writing the message
6. 6.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
7. 7.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
8. 8.⚖️ 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 kind of juice (c) the ironing time
9. 9.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) cutting the lemon (d) putting the iron away
10. 10.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
11. 11.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) an adult with an iron (d) a small bowl
13. 13.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
14. 14.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) plugging in the iron (c) ironing the paper (d) putting the iron away
15. 15.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) ironing the paper (d) letting the paper dry
16. 16.🛟 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
17. 17.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) a rainbow (d) blue words
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the iron setting (c) the kind of juice (d) how dark the writing is
20. 20.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) lemon juice (d) white paper
22. 22.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
24. 24.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a magnet (c) a balloon (d) yeast
25. 25.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
26. 26.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same paper
28. 28.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
29. 29.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
30. 30.True or false: reading the message is a job for an adult. (a) True (b) False
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
32. 32.⚖️ 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
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) a battery cell (d) an adult with an iron
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) a small bowl (d) white paper
35. 35.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
36. 36.⚖️ 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 kind of juice (c) the same cotton bud
37. 37.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
38. 38.True or false: writing the message is a job for an adult. (a) False (b) True
39. 39.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) brown (d) blue
40. 40.True or false: putting the iron away is a job a child can do. (a) False (b) True

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