Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 531 · 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) a small bowl (b) an adult with an iron (c) a battery cell (d) a cotton bud
2. 2.⚖️ 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 kind of juice (c) the same cotton bud
3. 3.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
4. 4.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) wash your hands (d) skip washing
5. 5.🍋 Which of these steps is a job for an adult? (a) writing the message (b) putting the iron away (c) dipping the cotton bud (d) letting the paper dry
6. 6.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
7. 7.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
8. 8.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) plugging in the iron (d) letting the paper dry
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) a balloon (d) lemon juice
10. 10.⚖️ 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 keep it the same (c) we change it
11. 11.True or false: putting the iron away is a job a child can do. (a) False (b) True
12. 12.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) heat adds colour (d) paper turns lemony
13. 13.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) dipping the cotton bud (d) reading the message
14. 14.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
15. 15.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) reading the message (d) ironing the paper
16. 16.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
17. 17.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
18. 18.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
19. 19.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) cutting the lemon (c) putting the iron away (d) ironing the paper
20. 20.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) ironing the paper (d) dipping the cotton bud
21. 21.🍋 Which of these steps is a job a child can do? (a) writing the message (b) plugging in the iron (c) cutting the lemon (d) putting the iron away
22. 22.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
24. 24.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
25. 25.⚖️ 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) how dark the writing is (d) the ironing time
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) lemon juice (d) a small bowl
27. 27.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
28. 28.True or false: turmeric powder is needed for the secret lemon message. (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) False (b) True
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
31. 31.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) dipping the cotton bud (d) plugging in the iron
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
33. 33.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
34. 34.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
35. 35.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
36. 36.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is magnetic (d) it is sticky
37. 37.True or false: reading the message is a job a child can do. (a) False (b) True
38. 38.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
39. 39.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
40. 40.⚖️ 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 measure it (c) we change it

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