Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 358 · 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 small bowl for the secret lemon message? (a) not needed (b) needed
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) whoever is fastest (d) the youngest child
3. 3.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) cutting the lemon (c) reading the message (d) dipping the cotton bud
4. 4.True or false: putting the iron away is a job for an adult. (a) False (b) True
5. 5.⚖️ 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 ironing time (c) the kind of juice
6. 6.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the kind of juice (d) the same paper
8. 8.⚖️ 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 measure it (c) we keep it the same
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) white paper (d) a cotton bud
11. 11.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) dark brown words (d) a rainbow
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) an adult with an iron (d) a magnet
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same paper (c) how dark the writing is (d) the same cotton bud
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) white paper (c) a cotton bud (d) an adult with an iron
16. 16.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) white (d) green
17. 17.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
18. 18.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
19. 19.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) dry juice is see-through (d) the paper ate it
20. 20.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) reading the message (d) plugging in the iron
21. 21.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) skip washing (d) rub your eyes
22. 22.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
23. 23.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) writing the message (d) ironing the paper
24. 24.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) the iron is brown (d) paper turns lemony
25. 25.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) dipping the cotton bud (d) reading the message
26. 26.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) plugging in the iron (c) reading the message (d) writing the message
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a balloon (c) lemon juice (d) a cotton bud
28. 28.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) turmeric powder (d) a magnet
29. 29.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
30. 30.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a magnet (c) a battery cell (d) yeast
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) lemon juice (c) a cotton bud (d) white paper
32. 32.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) ironing the paper (d) cutting the lemon
33. 33.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) writing the message (d) reading the message
34. 34.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a small bowl (c) an adult with an iron (d) lemon juice
36. 36.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
37. 37.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) putting the iron away (d) reading the message
38. 38.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
39. 39.🧺 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) a small bowl (d) a mirror
40. 40.True or false: ironing the paper is a job for an adult. (a) True (b) False

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