Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 796 · 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.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
2. 2.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) plugging in the iron
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
4. 4.⚖️ 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 cotton bud (c) the same paper (d) the ironing time
5. 5.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) plugging in the iron (d) reading the message
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) a small bowl (d) white paper
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) a small bowl (d) an adult with an iron
9. 9.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) dipping the cotton bud (c) reading the message (d) writing the message
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a small bowl (d) a balloon
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
12. 12.True or false: yeast is needed for the secret lemon message. (a) False (b) True
13. 13.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a mirror (c) a battery cell (d) a magnet
14. 14.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a mirror (c) an adult with an iron (d) lemon juice
17. 17.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words
18. 18.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) reading the message (d) putting the iron away
19. 19.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
20. 20.🍋 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
21. 21.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
22. 22.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if cooled (d) yes, if shaken
23. 23.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is cold (d) it is sticky
24. 24.True or false: ironing the paper is a job for an adult. (a) False (b) True
25. 25.True or false: reading the message is a job a child can do. (a) True (b) False
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) turmeric powder (d) lemon juice
27. 27.True or false: letting the paper dry is a job a child can do. (a) True (b) False
28. 28.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
29. 29.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
30. 30.True or false: white paper is needed for the secret lemon message. (a) False (b) True
31. 31.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) lemon juice (d) a mirror
32. 32.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) a magnet (d) a small bowl
34. 34.True or false: ironing the paper is a job a child can do. (a) True (b) False
35. 35.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
36. 36.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
37. 37.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a battery cell (d) a small bowl
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a cotton bud (d) white paper
40. 40.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False

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