Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 296 · 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.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the iron setting (d) the same paper
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) an adult with an iron (d) lemon juice
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
5. 5.⚖️ 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
6. 6.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
7. 7.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) an adult with an iron (c) a small bowl (d) white paper
9. 9.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
10. 10.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
11. 11.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
12. 12.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
13. 13.⚖️ 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 iron setting (c) the kind of juice
14. 14.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
15. 15.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is sticky (d) it is magnetic
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) an adult with an iron (d) lemon juice
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) yeast (d) white paper
18. 18.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) writing the message (c) plugging in the iron (d) ironing the paper
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) a mirror (d) lemon juice
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
22. 22.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) putting the iron away (d) dipping the cotton bud
23. 23.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) letting the paper dry (d) plugging in the iron
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.True or false: plugging in the iron is a job for an adult. (a) True (b) False
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) how dark the writing is (c) the iron setting (d) the same cotton bud
27. 27.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) putting the iron away (d) reading the message
28. 28.⚖️ 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
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
30. 30.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) heat adds colour (c) paper turns lemony (d) the iron is brown
31. 31.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) it gets darker (d) the paper floats
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a mirror (c) a cotton bud (d) lemon juice
33. 33.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
34. 34.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) plugging in the iron (d) dipping the cotton bud
35. 35.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) white paper (d) turmeric powder
37. 37.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
38. 38.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) plugging in the iron (c) writing the message (d) reading the message
39. 39.True or false: letting the paper dry is a job for an adult. (a) False (b) True
40. 40.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) ironing the paper (d) letting the paper dry

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