Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 526 · 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) putting the iron away (b) dipping the cotton bud (c) letting the paper dry (d) writing the message
2. 2.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the ironing time (c) how dark the writing is (d) the kind of juice
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) white paper (d) a magnet
6. 6.True or false: writing the message is a job a child can do. (a) True (b) False
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a battery cell (c) a cotton bud (d) white paper
8. 8.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) a balloon (d) an adult with an iron
9. 9.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) letting the paper dry (d) dipping the cotton bud
10. 10.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
11. 11.🍋 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
12. 12.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
13. 13.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
14. 14.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) turmeric powder (d) a cotton bud
16. 16.🍋 Which of these steps is a job for an adult? (a) reading the message (b) plugging in the iron (c) dipping the cotton bud (d) letting the paper dry
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) white paper (d) a magnet
18. 18.True or false: white paper is needed for the secret lemon message. (a) False (b) True
19. 19.🍋 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
20. 20.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
21. 21.True or false: cutting the lemon is a job a child can do. (a) False (b) True
22. 22.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud 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 ironing time”? (a) we change it (b) we keep it the same (c) we measure it
25. 25.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
26. 26.🛟 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
27. 27.🛟 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
28. 28.True or false: letting the paper dry is a job a child can do. (a) False (b) True
29. 29.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
30. 30.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
33. 33.True or false: reading the message is a job a child can do. (a) True (b) False
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) white paper (c) a cotton bud (d) an adult with an iron
35. 35.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
36. 36.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) ironing the paper (d) letting the paper dry
37. 37.⚖️ 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) the same paper (c) the ironing time (d) how dark the writing is
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) yeast (c) a cotton bud (d) a small bowl
39. 39.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
40. 40.⚖️ 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

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