Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 602 · 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) a child can do it (b) an adult does it
2. 2.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
3. 3.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
4. 4.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) yeast (d) white paper
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
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) True (b) False
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) white paper (d) a magnet
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a small bowl (d) a balloon
10. 10.🍋 Which of these steps is a job a child can do? (a) writing the message (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
11. 11.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
12. 12.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) ironing the paper
13. 13.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) ironing the paper (d) cutting the lemon
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a magnet (d) a cotton bud
15. 15.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
16. 16.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) letting the paper dry (c) ironing the paper (d) cutting the lemon
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the same paper (c) the same cotton bud (d) the kind of juice
18. 18.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) brown (d) blue
19. 19.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is sticky (d) it is cold
20. 20.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if cooled (d) yes, if shaken
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) an adult with an iron (d) yeast
22. 22.🔮 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
23. 23.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the iron is brown (d) the juice scorches first
24. 24.⚖️ 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
25. 25.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) letting the paper dry (d) dipping the cotton bud
26. 26.⚖️ 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
27. 27.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) cutting the lemon
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) white paper (d) a battery cell
29. 29.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a cotton bud (c) an adult with an iron (d) lemon juice
31. 31.🧺 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) lemon juice (d) turmeric powder
32. 32.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) chemical (d) magnetic
33. 33.⚖️ 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 same cotton bud (c) how dark the writing is
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
35. 35.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
36. 36.True or false: reading the message is a job for an adult. (a) True (b) False
37. 37.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
38. 38.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
39. 39.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
40. 40.True or false: white paper is not needed for the secret lemon message. (a) True (b) False

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