Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 614 · 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) reading the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
2. 2.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) plugging in the iron
3. 3.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) writing the message (d) putting the iron away
4. 4.🧺 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) lemon juice (d) a magnet
5. 5.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
6. 6.🍋 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
7. 7.🔍 Which is the odd one out? (a) letting the paper dry (b) putting the iron away (c) reading the message (d) writing the message
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) any child (d) whoever is fastest
9. 9.⚖️ 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
10. 10.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) writing the message (d) reading the message
11. 11.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
12. 12.⚖️ 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 iron setting (d) the same cotton bud
13. 13.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
14. 14.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) a rainbow (d) blue words
15. 15.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
16. 16.⚖️ 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 keep it the same (c) we measure it
17. 17.⚖️ 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
18. 18.True or false: writing the message is a job a child can do. (a) False (b) True
19. 19.⚖️ 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
20. 20.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the kind of juice (d) the same cotton bud
22. 22.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
23. 23.⚖️ 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
24. 24.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
25. 25.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
27. 27.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) no, it stays brown (d) yes, in the dark
28. 28.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) a small bowl (d) lemon juice
30. 30.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) the paper floats (d) writing turns green
31. 31.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) white paper (d) a battery cell
33. 33.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
34. 34.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a balloon (d) an adult with an iron
36. 36.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) letting the paper dry (d) putting the iron away
37. 37.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
38. 38.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) dipping the cotton bud (d) ironing the paper
39. 39.True or false: letting the paper dry is a job for an adult. (a) True (b) False
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a mirror (c) a small bowl (d) white paper

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