Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 849 · 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 is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) writing the message
2. 2.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) writing the message (d) cutting the lemon
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a mirror (c) an adult with an iron (d) a small bowl
4. 4.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
5. 5.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
6. 6.True or false: ironing the paper is a job a child can do. (a) True (b) False
7. 7.⚖️ 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
8. 8.True or false: putting the iron away is a job a child can do. (a) False (b) True
9. 9.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
10. 10.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
11. 11.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the kind of juice (c) the same cotton bud (d) how dark the writing is
13. 13.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a cotton bud (d) turmeric powder
15. 15.🍋 Which of these steps is a job for an adult? (a) writing the message (b) ironing the paper (c) letting the paper dry (d) dipping the cotton bud
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
17. 17.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) brown (d) green
18. 18.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
19. 19.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) reading the message (d) cutting the lemon
20. 20.⚖️ 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
21. 21.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
22. 22.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the paper ate it (d) the ink is magnetic
23. 23.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) writing the message (d) letting the paper dry
24. 24.⚖️ 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
25. 25.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
26. 26.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
27. 27.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) plugging in the iron (d) writing the message
28. 28.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
29. 29.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
30. 30.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) reading the message (d) writing the message
31. 31.⚖️ 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
32. 32.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
33. 33.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) yeast (c) a battery cell (d) a balloon
34. 34.True or false: cutting the lemon is a job for an adult. (a) False (b) True
35. 35.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
36. 36.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
37. 37.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
39. 39.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) plugging in the iron
40. 40.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True

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