Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 599 · 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.True or false: putting the iron away is a job for an adult. (a) False (b) True
2. 2.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
3. 3.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) ironing the paper
4. 4.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) white paper (d) a small bowl
6. 6.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a balloon (c) a cotton bud (d) an adult with an iron
8. 8.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) dipping the cotton bud
9. 9.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) letting the paper dry (d) writing the message
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the same cotton bud (c) the iron setting (d) how dark the writing is
11. 11.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
12. 12.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) writing the message
13. 13.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) ironing the paper (d) plugging in the iron
14. 14.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
16. 16.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) ironing the paper (d) cutting the lemon
17. 17.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
18. 18.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
19. 19.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
20. 20.⚖️ 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 change it (c) we measure it
21. 21.True or false: reading the message is a job for an adult. (a) True (b) False
22. 22.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
23. 23.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) cutting the lemon (d) writing the message
24. 24.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a magnet (c) a battery cell (d) a mirror
25. 25.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical
26. 26.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) the iron is brown (d) paper turns lemony
27. 27.🧺 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
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
29. 29.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
30. 30.True or false: cutting the lemon is a job for an adult. (a) False (b) True
31. 31.True or false: writing the message is a job a child can do. (a) False (b) True
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
33. 33.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) brown (d) green
34. 34.True or false: ironing the paper is a job for an adult. (a) False (b) True
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) an adult with an iron (c) a small bowl (d) lemon juice
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
38. 38.True or false: plugging in the iron is a job a child can do. (a) True (b) False
39. 39.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
40. 40.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it can burn skin (d) it is cold

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