Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 130 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
2. 2.⚖️ 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
3. 3.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
4. 4.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) dipping the cotton bud (d) putting the iron away
5. 5.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) reading the message (d) ironing the paper
6. 6.🛟 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
7. 7.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) writing the message
8. 8.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
9. 9.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
10. 10.True or false: yeast is needed for the secret lemon message. (a) True (b) False
11. 11.⚖️ 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 change it (c) we keep it the same
12. 12.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
13. 13.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) brown (d) blue
14. 14.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
15. 15.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) wash your hands (d) skip washing
16. 16.⚖️ 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 ironing time
17. 17.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
18. 18.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
19. 19.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) a balloon (d) a small bowl
21. 21.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
22. 22.⚖️ 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 measure it (c) we keep it the same
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) an adult with an iron (d) a magnet
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) white paper (d) lemon juice
25. 25.True or false: writing the message is a job for an adult. (a) True (b) False
26. 26.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
27. 27.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) putting the iron away
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
29. 29.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) ironing the paper (d) reading the message
30. 30.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical
31. 31.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) cutting the lemon
32. 32.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a balloon (c) a small bowl (d) lemon juice
34. 34.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
35. 35.True or false: plugging in the iron is a job for an adult. (a) True (b) False
36. 36.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
37. 37.⚖️ 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
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a cotton bud (c) an adult with an iron (d) lemon juice
39. 39.⚖️ 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 same cotton bud (c) the kind of juice
40. 40.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) letting the paper dry

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