Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 523 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) white paper (d) a cotton bud
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a small bowl (c) a cotton bud (d) an adult with an iron
3. 3.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) writing the message (d) letting the paper dry
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) yeast (d) a cotton bud
5. 5.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) any child (d) the youngest child
6. 6.⚖️ 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 measure it (c) we keep it the same
7. 7.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) putting the iron away
8. 8.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, in the dark (d) yes, if shaken
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a balloon (d) lemon juice
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a battery cell (d) a cotton bud
11. 11.True or false: plugging in the iron is a job for an adult. (a) False (b) True
12. 12.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
13. 13.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
14. 14.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) letting the paper dry
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) lemon juice (c) a cotton bud (d) white paper
16. 16.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a mirror (d) white paper
18. 18.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
19. 19.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
20. 20.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) it gets darker (d) writing turns green
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a cotton bud (d) a battery cell
22. 22.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
25. 25.🛟 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
26. 26.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) paper turns lemony (d) the juice scorches first
27. 27.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
28. 28.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
30. 30.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
31. 31.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
32. 32.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) an adult with an iron (c) white paper (d) a small bowl
34. 34.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) putting the iron away (d) writing the message
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
36. 36.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
37. 37.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
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 same paper (b) the kind of juice (c) the ironing time (d) how dark the writing is
39. 39.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it can burn skin (d) it is magnetic
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a battery cell (d) lemon juice

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