Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 91 · 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? Which of these is the one thing we change? (a) the same paper (b) the kind of juice (c) how dark the writing is (d) the same cotton bud
2. 2.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is magnetic (d) it is sticky
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a mirror (c) an adult with an iron (d) a small bowl
5. 5.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
6. 6.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) the iron is brown (d) heat adds colour
7. 7.⚖️ 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
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) lemon juice (c) a battery cell (d) a magnet
9. 9.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
11. 11.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) yeast (d) an adult with an iron
13. 13.⚖️ 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 paper (c) how dark the writing is
14. 14.⚖️ 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 kind of juice (d) how dark the writing is
15. 15.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
16. 16.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) plugging in the iron (d) letting the paper dry
17. 17.⚖️ 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
18. 18.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
19. 19.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) turmeric powder (c) a balloon (d) a magnet
20. 20.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
21. 21.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
22. 22.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
23. 23.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
24. 24.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
25. 25.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
26. 26.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) writing the message (d) plugging in the iron
27. 27.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
28. 28.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) a magnet
30. 30.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) cutting the lemon (d) putting the iron away
31. 31.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
32. 32.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
33. 33.True or false: plugging in the iron is a job a child can do. (a) True (b) False
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) a small bowl (c) lemon juice (d) a cotton bud
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) a balloon (d) a cotton bud
36. 36.True or false: an adult with an iron is not 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: the kind of juice is kept the same. (a) False (b) True
38. 38.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
39. 39.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
40. 40.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing

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