Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 153 · 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) white paper (b) a cotton bud (c) yeast (d) an adult with an iron
2. 2.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the juice scorches first (d) the iron is brown
3. 3.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
4. 4.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
5. 5.True or false: ironing the paper is a job for an adult. (a) True (b) False
6. 6.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) cutting the lemon
7. 7.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
8. 8.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
9. 9.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) blue (d) brown
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a balloon (c) a cotton bud (d) lemon juice
11. 11.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) plugging in the iron
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) an adult with an iron (d) turmeric powder
13. 13.True or false: cutting the lemon is a job for an adult. (a) True (b) False
14. 14.⚖️ 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
15. 15.⚖️ 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 keep it the same (c) we change it
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) turmeric powder (d) white paper
17. 17.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is magnetic (d) it is cold
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) lemon juice (d) a magnet
19. 19.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
21. 21.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
22. 22.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
23. 23.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
24. 24.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
25. 25.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) no, it stays brown (d) yes, if shaken
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
27. 27.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a small bowl (d) a battery cell
29. 29.⚖️ 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
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
31. 31.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) dipping the cotton bud
32. 32.True or false: yeast is needed for the secret lemon message. (a) True (b) False
33. 33.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) a battery cell (d) lemon juice
34. 34.True or false: plugging in the iron is a job a child can do. (a) True (b) False
35. 35.⚖️ 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 cotton bud (c) the kind of juice (d) how dark the writing is
36. 36.True or false: ironing the paper is a job a child can do. (a) False (b) True
37. 37.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
38. 38.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) white paper (d) lemon juice
40. 40.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) chemical (d) magnetic

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