Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 314 · 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.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
2. 2.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) an adult with an iron (c) a magnet (d) a balloon
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) lemon juice (d) an adult with an iron
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
5. 5.🔮 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
6. 6.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
7. 7.True or false: cutting the lemon is a job for an adult. (a) True (b) False
8. 8.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
9. 9.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) dipping the cotton bud (d) cutting the lemon
10. 10.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) reading the message
11. 11.⚖️ 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) the iron setting (c) how dark the writing is
12. 12.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) the paper floats (d) writing turns green
13. 13.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
14. 14.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) a magnet (d) a battery cell
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) a battery cell (d) lemon juice
16. 16.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
17. 17.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
18. 18.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) the paper ate it (d) dry juice is see-through
19. 19.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) putting the iron away (d) reading the message
20. 20.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
21. 21.True or false: ironing the paper is a job a child can do. (a) True (b) False
22. 22.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) almost nothing (d) a rainbow
23. 23.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
24. 24.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a magnet (d) lemon juice
27. 27.True or false: putting the iron away is a job a child can do. (a) True (b) False
28. 28.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a cotton bud (d) an adult with an iron
30. 30.True or false: writing the message is a job a child can do. (a) False (b) True
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a cotton bud (c) a small bowl (d) an adult with an iron
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
33. 33.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) magnetic (d) physical
34. 34.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) blue (d) green
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
36. 36.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) reading the message (d) plugging in the iron
37. 37.True or false: ironing the paper is a job for an adult. (a) True (b) False
38. 38.🍋 Which of these steps is a job for an adult? (a) writing the message (b) ironing the paper (c) letting the paper dry (d) reading the message
39. 39.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
40. 40.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is sticky (d) it is cold

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