Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 722 · 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) writing the message (b) ironing the paper (c) dipping the cotton bud (d) reading the message
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) yeast (c) a small bowl (d) lemon juice
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the same paper (d) the iron setting
5. 5.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a balloon (c) a magnet (d) a mirror
6. 6.True or false: cutting the lemon is a job for an adult. (a) False (b) True
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a small bowl (d) a magnet
8. 8.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
9. 9.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
10. 10.True or false: ironing the paper is a job a child can do. (a) True (b) False
11. 11.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) rub your eyes (d) skip washing
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) turmeric powder (d) lemon juice
13. 13.⚖️ 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
14. 14.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) cutting the lemon (d) putting the iron away
15. 15.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) reading the message (d) writing the message
16. 16.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is cold (d) it is magnetic
17. 17.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) letting the paper dry
18. 18.⚖️ 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
19. 19.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a battery cell (d) lemon juice
21. 21.True or false: letting the paper dry is a job for an adult. (a) True (b) False
22. 22.🔮 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
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
24. 24.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) writing the message (d) dipping the cotton bud
25. 25.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
26. 26.True or false: plugging in the iron is a job a child can do. (a) False (b) True
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a small bowl (c) white paper (d) a cotton bud
28. 28.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
29. 29.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
30. 30.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a cotton bud (d) a magnet
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
33. 33.True or false: putting the iron away is a job for an adult. (a) True (b) False
34. 34.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) it turned into air (d) the ink is magnetic
35. 35.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
37. 37.⚖️ 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
38. 38.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) writing the message
39. 39.🔮 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
40. 40.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) dipping the cotton bud (d) cutting the lemon

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