Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 835 · 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 of these is needed for the secret lemon message? (a) a mirror (b) a small bowl (c) a magnet (d) a balloon
2. 2.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) letting the paper dry (c) reading the message (d) dipping the cotton bud
3. 3.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
4. 4.⚖️ 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
5. 5.🍋 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) dipping the cotton bud
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
7. 7.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
8. 8.🧺 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) yeast
9. 9.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) ironing the paper (d) cutting the lemon
10. 10.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
11. 11.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
12. 12.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) reading the message (d) letting the paper dry
13. 13.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
14. 14.⚖️ 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
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same paper (c) the same cotton bud (d) the ironing time
17. 17.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
18. 18.True or false: yeast is needed for the secret lemon message. (a) False (b) True
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) an adult with an iron (d) lemon juice
20. 20.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
21. 21.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) reading the message (c) dipping the cotton bud (d) letting the paper dry
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) white paper (d) a small bowl
23. 23.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) letting the paper dry (c) ironing the paper (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 iron setting”? (a) we keep it the same (b) we change it (c) we measure it
25. 25.True or false: letting the paper dry is a job a child can do. (a) False (b) True
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
28. 28.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
29. 29.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) the paper floats (d) writing stays faint
30. 30.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
31. 31.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
32. 32.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
33. 33.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
34. 34.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) a balloon (d) lemon juice
35. 35.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the iron is brown (d) the juice scorches first
36. 36.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a battery cell (c) a magnet (d) a balloon
37. 37.True or false: plugging in the iron is a job a child can do. (a) True (b) False
38. 38.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
39. 39.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
40. 40.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) ironing the paper

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