Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 193 · 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.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
2. 2.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) white paper (d) lemon juice
4. 4.🧺 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 battery cell (d) a small bowl
5. 5.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
6. 6.True or false: plugging in the iron is a job a child can do. (a) True (b) False
7. 7.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) cutting the lemon
8. 8.True or false: ironing the paper is a job for an adult. (a) False (b) True
9. 9.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
10. 10.🍋 Which of these steps is a job a child can do? (a) writing the message (b) plugging in the iron (c) putting the iron away (d) cutting the lemon
11. 11.🛟 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
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
13. 13.🛟 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
14. 14.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) yeast (d) a cotton bud
16. 16.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) a balloon (d) a mirror
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) lemon juice (d) an adult with an iron
18. 18.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
19. 19.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) dipping the cotton bud (d) cutting the lemon
20. 20.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) paper turns lemony (d) the juice scorches first
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
22. 22.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) plugging in the iron (d) reading the message
23. 23.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) a cotton bud (d) a balloon
24. 24.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) a balloon (d) turmeric powder
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the iron setting (c) the same paper (d) the ironing time
26. 26.⚖️ 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
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 change it (c) we keep it the same
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) an adult with an iron (d) lemon juice
29. 29.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
30. 30.⚖️ 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
31. 31.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) cutting the lemon (d) writing the message
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
33. 33.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
34. 34.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
35. 35.⚖️ 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
36. 36.⚖️ 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
37. 37.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) writing the message (d) reading the message
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) a cotton bud (c) a small bowl (d) white paper
39. 39.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
40. 40.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True

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