Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 215 · 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.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a magnet (d) a balloon
2. 2.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) yeast (d) white paper
4. 4.True or false: ironing the paper is a job for an adult. (a) True (b) False
5. 5.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
6. 6.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
7. 7.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) plugging in the iron (d) cutting the lemon
8. 8.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
9. 9.True or false: cutting the lemon is a job for an adult. (a) True (b) False
10. 10.⚖️ 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 keep it the same (c) we measure it
11. 11.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) a cotton bud (d) an adult with an iron
13. 13.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
14. 14.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
16. 16.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
17. 17.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
18. 18.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) ironing the paper (d) cutting the lemon
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a cotton bud (d) yeast
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) yeast (d) a small bowl
22. 22.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
23. 23.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
24. 24.⚖️ 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 same cotton bud (c) the ironing time (d) the kind of juice
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
26. 26.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
27. 27.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) cutting the lemon
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a battery cell (c) a small bowl (d) an adult with an iron
29. 29.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
30. 30.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
31. 31.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
32. 32.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) ironing the paper
33. 33.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) it gets darker (d) writing turns green
34. 34.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) the juice scorches first (d) heat adds colour
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) turmeric powder (d) a mirror
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) lemon juice (c) an adult with an iron (d) white paper
37. 37.🧺 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) turmeric powder (d) a cotton bud
38. 38.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
39. 39.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a battery cell (d) a magnet
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same

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