Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 694 · 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 a cotton bud for the secret lemon message? (a) not needed (b) needed
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) yeast (d) an adult with an iron
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
4. 4.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) cutting the lemon (d) reading the message
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) dark brown words (d) blue words
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) white paper (d) a cotton bud
7. 7.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
8. 8.True or false: plugging in the iron is a job for an adult. (a) False (b) True
9. 9.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
10. 10.⚖️ 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 paper (c) the same cotton bud (d) the ironing time
11. 11.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) lemon juice (d) yeast
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a mirror (d) a cotton bud
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a balloon (d) a small bowl
16. 16.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) rub your eyes (d) lick your fingers
17. 17.True or false: plugging in the iron is a job a child can do. (a) True (b) False
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the iron setting (c) the same paper (d) the kind of juice
19. 19.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) dry juice is see-through (d) it turned into air
20. 20.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) a mirror (d) an adult with an iron
22. 22.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
24. 24.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) putting the iron away (d) ironing the paper
25. 25.True or false: writing the message is a job for an adult. (a) True (b) False
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) a battery cell (d) lemon juice
27. 27.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
28. 28.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
29. 29.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) putting the iron away
30. 30.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) dipping the cotton bud (d) ironing the paper
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) white paper (c) a cotton bud (d) lemon juice
32. 32.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) green (d) brown
33. 33.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) turmeric powder (d) white paper
35. 35.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
36. 36.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) dipping the cotton bud (d) letting the paper dry
37. 37.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) letting the paper dry (c) plugging in the iron (d) putting the iron away
38. 38.⚖️ 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
39. 39.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
40. 40.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) putting the iron away

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