Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 662 · 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.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
2. 2.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) the juice scorches first (d) paper turns lemony
3. 3.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
5. 5.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it can burn skin (d) it is magnetic
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) white paper (c) lemon juice (d) a cotton bud
7. 7.🛟 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
8. 8.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
9. 9.True or false: letting the paper dry is a job a child can do. (a) False (b) True
10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) the youngest child (d) any child
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the same paper (d) the kind of juice
12. 12.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) reading the message (d) plugging in the iron
13. 13.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) plugging in the iron (d) dipping the cotton bud
14. 14.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) a small bowl (d) a balloon
15. 15.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a small bowl (c) lemon juice (d) a cotton bud
17. 17.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a cotton bud (d) white paper
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
20. 20.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) letting the paper dry (c) plugging in the iron (d) cutting the lemon
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) an adult with an iron (d) yeast
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) turmeric powder (d) a small bowl
23. 23.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
24. 24.True or false: ironing the paper is a job for an adult. (a) False (b) True
25. 25.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) ironing the paper
26. 26.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
27. 27.⚖️ 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 keep it the same (c) we change it
28. 28.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
29. 29.⚖️ 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
30. 30.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
31. 31.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) reading the message (d) dipping the cotton bud
32. 32.⚖️ 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 measure it (c) we change it
33. 33.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
34. 34.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
37. 37.True or false: letting the paper dry is a job for an adult. (a) False (b) True
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a small bowl (d) yeast
39. 39.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
40. 40.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed

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