Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 281 · 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: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) a rainbow (d) almost nothing
2. 2.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
3. 3.⚖️ 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
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
5. 5.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
6. 6.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) ironing the paper
7. 7.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
9. 9.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
10. 10.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) putting the iron away (d) letting the paper dry
11. 11.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) a mirror (d) lemon juice
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
13. 13.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) plugging in the iron (d) cutting the lemon
14. 14.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
15. 15.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) turmeric powder (c) lemon juice (d) an adult with an iron
17. 17.🔮 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
18. 18.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) writing the message (d) plugging in the iron
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a mirror (d) lemon juice
20. 20.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
21. 21.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
24. 24.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) brown (d) blue
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
26. 26.🔍 Which is the odd one out? (a) letting the paper dry (b) putting the iron away (c) cutting the lemon (d) plugging in the iron
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
28. 28.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a small bowl (c) an adult with an iron (d) a cotton bud
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the same cotton bud (c) the kind of juice
31. 31.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) reading the message
32. 32.True or false: reading the message is a job for an adult. (a) True (b) False
33. 33.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
34. 34.True or false: putting the iron away is a job for an adult. (a) True (b) False
35. 35.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) a small bowl (d) a battery cell
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) yeast (d) white paper
37. 37.🍋 Which of these steps is a job a child can do? (a) reading the message (b) ironing the paper (c) putting the iron away (d) cutting the lemon
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the kind of juice (c) the same cotton bud (d) the ironing time
39. 39.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
40. 40.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False

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